

<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.synchronoss.com/role/AccumulatedOtherComprehensiveIncomeLoss" xlink:href="sncr-20160930.xsd#AccumulatedOtherComprehensiveIncomeLoss" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/AccumulatedOtherComprehensiveIncomeLossChangesInAociDetails" xlink:href="sncr-20160930.xsd#AccumulatedOtherComprehensiveIncomeLossChangesInAociDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/AccumulatedOtherComprehensiveIncomeLossComprehensiveIncomeDetails" xlink:href="sncr-20160930.xsd#AccumulatedOtherComprehensiveIncomeLossComprehensiveIncomeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/AccumulatedOtherComprehensiveIncomeLossTables" xlink:href="sncr-20160930.xsd#AccumulatedOtherComprehensiveIncomeLossTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/Acquisition" xlink:href="sncr-20160930.xsd#Acquisition" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/Acquisition2016AcquisitionsOpenwaveDetails" xlink:href="sncr-20160930.xsd#Acquisition2016AcquisitionsOpenwaveDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/AcquisitionTables" xlink:href="sncr-20160930.xsd#AcquisitionTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/BasisOfPresentationAndConsolidation" xlink:href="sncr-20160930.xsd#BasisOfPresentationAndConsolidation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/BasisOfPresentationAndConsolidationEarlyAdoptionDetails" xlink:href="sncr-20160930.xsd#BasisOfPresentationAndConsolidationEarlyAdoptionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/BasisOfPresentationAndConsolidationNewAccountingPronouncementsDetails" xlink:href="sncr-20160930.xsd#BasisOfPresentationAndConsolidationNewAccountingPronouncementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/BasisOfPresentationAndConsolidationPolicies" xlink:href="sncr-20160930.xsd#BasisOfPresentationAndConsolidationPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/BasisOfPresentationAndConsolidationTables" xlink:href="sncr-20160930.xsd#BasisOfPresentationAndConsolidationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:href="sncr-20160930.xsd#CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:href="sncr-20160930.xsd#CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:href="sncr-20160930.xsd#CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/CondensedConsolidatedStatementsOfIncomeAndComprehensiveIncomeUnaudited" xlink:href="sncr-20160930.xsd#CondensedConsolidatedStatementsOfIncomeAndComprehensiveIncomeUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/Debt" xlink:href="sncr-20160930.xsd#Debt" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/DebtConvertibleSeniorNotesDetails" xlink:href="sncr-20160930.xsd#DebtConvertibleSeniorNotesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/DebtCreditFacilityDetails" xlink:href="sncr-20160930.xsd#DebtCreditFacilityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/DebtTables" xlink:href="sncr-20160930.xsd#DebtTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/DescriptionOfBusiness" xlink:href="sncr-20160930.xsd#DescriptionOfBusiness" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/DocumentAndEntityInformation" xlink:href="sncr-20160930.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/EarningsPerCommonShare" xlink:href="sncr-20160930.xsd#EarningsPerCommonShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/EarningsPerCommonShareDetails" xlink:href="sncr-20160930.xsd#EarningsPerCommonShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/EarningsPerCommonShareTables" xlink:href="sncr-20160930.xsd#EarningsPerCommonShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilities" xlink:href="sncr-20160930.xsd#FairValueMeasurementsOfAssetsAndLiabilities" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesAfsSecuritiesDetails" xlink:href="sncr-20160930.xsd#FairValueMeasurementsOfAssetsAndLiabilitiesAfsSecuritiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesAfsSecuritiesExpectedMaturitiesDetails" xlink:href="sncr-20160930.xsd#FairValueMeasurementsOfAssetsAndLiabilitiesAfsSecuritiesExpectedMaturitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesAfsSecuritiesInUnrealizedLossPositionDetails" xlink:href="sncr-20160930.xsd#FairValueMeasurementsOfAssetsAndLiabilitiesAfsSecuritiesInUnrealizedLossPositionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesHeirarchyDetails" xlink:href="sncr-20160930.xsd#FairValueMeasurementsOfAssetsAndLiabilitiesHeirarchyDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesLevel3ContingentConsiderationDetails" xlink:href="sncr-20160930.xsd#FairValueMeasurementsOfAssetsAndLiabilitiesLevel3ContingentConsiderationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesLevel3RedeemableNoncontrollingInterestsDetails" xlink:href="sncr-20160930.xsd#FairValueMeasurementsOfAssetsAndLiabilitiesLevel3RedeemableNoncontrollingInterestsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesTables" xlink:href="sncr-20160930.xsd#FairValueMeasurementsOfAssetsAndLiabilitiesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/GoodwillAndIntangibles" xlink:href="sncr-20160930.xsd#GoodwillAndIntangibles" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/GoodwillAndIntangiblesGoodwillDetails" xlink:href="sncr-20160930.xsd#GoodwillAndIntangiblesGoodwillDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/GoodwillAndIntangiblesIntangibleAssetsDetails" xlink:href="sncr-20160930.xsd#GoodwillAndIntangiblesIntangibleAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/GoodwillAndIntangiblesIntangibleAssetsFutureAmortizationDetails" xlink:href="sncr-20160930.xsd#GoodwillAndIntangiblesIntangibleAssetsFutureAmortizationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/GoodwillAndIntangiblesTables" xlink:href="sncr-20160930.xsd#GoodwillAndIntangiblesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/IncomeTaxes" xlink:href="sncr-20160930.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/IncomeTaxesDetails" xlink:href="sncr-20160930.xsd#IncomeTaxesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/LegalMatters" xlink:href="sncr-20160930.xsd#LegalMatters" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/LegalMattersDetails" xlink:href="sncr-20160930.xsd#LegalMattersDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/Restructuring" xlink:href="sncr-20160930.xsd#Restructuring" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/RestructuringDetails" xlink:href="sncr-20160930.xsd#RestructuringDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/RestructuringTables" xlink:href="sncr-20160930.xsd#RestructuringTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/StockholdersEquity" xlink:href="sncr-20160930.xsd#StockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/StockholdersEquityBlackScholesAssumptionsDetails" xlink:href="sncr-20160930.xsd#StockholdersEquityBlackScholesAssumptionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/StockholdersEquityEsppAndOtherDisclosuresDetails" xlink:href="sncr-20160930.xsd#StockholdersEquityEsppAndOtherDisclosuresDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/StockholdersEquityRestrictedStockDetails" xlink:href="sncr-20160930.xsd#StockholdersEquityRestrictedStockDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/StockholdersEquityStockBasedCompensationDetails" xlink:href="sncr-20160930.xsd#StockholdersEquityStockBasedCompensationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/StockholdersEquityStockOptionsDetails" xlink:href="sncr-20160930.xsd#StockholdersEquityStockOptionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/StockholdersEquityTables" xlink:href="sncr-20160930.xsd#StockholdersEquityTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/StockholdersEquityTreasuryStockDetails" xlink:href="sncr-20160930.xsd#StockholdersEquityTreasuryStockDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.synchronoss.com/role/SubsequentEventsReview" xlink:href="sncr-20160930.xsd#SubsequentEventsReview" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/AccumulatedOtherComprehensiveIncomeLoss" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/AccumulatedOtherComprehensiveIncomeLossChangesInAociDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_6F9B5A211E3FEC85E7E9070CDF06DB04" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_FBD966A7F7B9BF31D831070CDF06FFEB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_6F9B5A211E3FEC85E7E9070CDF06DB04" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_FBD966A7F7B9BF31D831070CDF06FFEB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_D5A5A08A98CE1AD2A5FA070CDF06C6E1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_FBD966A7F7B9BF31D831070CDF06FFEB" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_D5A5A08A98CE1AD2A5FA070CDF06C6E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_402891E979E3EDC445C3070CDF061BB4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_D5A5A08A98CE1AD2A5FA070CDF06C6E1" xlink:to="loc_us-gaap_EquityComponentDomain_402891E979E3EDC445C3070CDF061BB4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_402891E979E3EDC445C3070CDF061BB4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_D5A5A08A98CE1AD2A5FA070CDF06C6E1" xlink:to="loc_us-gaap_EquityComponentDomain_402891E979E3EDC445C3070CDF061BB4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_59D63AB51284DCB2A4CC070CDF060A58" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_402891E979E3EDC445C3070CDF061BB4" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_59D63AB51284DCB2A4CC070CDF060A58" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedTranslationAdjustmentMember" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_4EC987A9115EC343797D070CDF061408" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_59D63AB51284DCB2A4CC070CDF060A58" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_4EC987A9115EC343797D070CDF061408" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_AccumulatedNetGainLossOnIntraEntityForeignCurrencyTransactionsMember" xlink:label="loc_sncr_AccumulatedNetGainLossOnIntraEntityForeignCurrencyTransactionsMember_E5B1371E0F3A62AAAD5A070CDF06A962" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_59D63AB51284DCB2A4CC070CDF060A58" xlink:to="loc_sncr_AccumulatedNetGainLossOnIntraEntityForeignCurrencyTransactionsMember_E5B1371E0F3A62AAAD5A070CDF06A962" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember" xlink:label="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_F63F59B391D3489C427E070CDF066354" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_59D63AB51284DCB2A4CC070CDF060A58" xlink:to="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_F63F59B391D3489C427E070CDF066354" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_8BA29F1E2542CE5B816C070CDF064877" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_6F9B5A211E3FEC85E7E9070CDF06DB04" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_8BA29F1E2542CE5B816C070CDF064877" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_E756FDD358479B2E5054070CDF0658B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_8BA29F1E2542CE5B816C070CDF064877" xlink:to="loc_us-gaap_StockholdersEquity_E756FDD358479B2E5054070CDF0658B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent_47C5B7F20066E4B1719B070CDF07BA73" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_8BA29F1E2542CE5B816C070CDF064877" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent_47C5B7F20066E4B1719B070CDF07BA73" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_BEF82DFA4B0015EC576C070CDF071E66" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_8BA29F1E2542CE5B816C070CDF064877" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_BEF82DFA4B0015EC576C070CDF071E66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_E80BE067BDC645E94ADE070CDF0C9211" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_8BA29F1E2542CE5B816C070CDF064877" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_E80BE067BDC645E94ADE070CDF0C9211" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/AccumulatedOtherComprehensiveIncomeLossComprehensiveIncomeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/AccumulatedOtherComprehensiveIncomeLossTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/Acquisition" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/Acquisition2016AcquisitionsOpenwaveDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_F55C5C6351C2FF87406D772FE86C31DB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6FC6821702A32EA91527772FE86B1397" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_F55C5C6351C2FF87406D772FE86C31DB" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6FC6821702A32EA91527772FE86B1397" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_DAC2DA35B4E5F25573CE772FE86BA5CA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6FC6821702A32EA91527772FE86B1397" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_DAC2DA35B4E5F25573CE772FE86BA5CA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7D18D177930CCC46EC7D772FE86BEF6F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_DAC2DA35B4E5F25573CE772FE86BA5CA" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7D18D177930CCC46EC7D772FE86BEF6F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7D18D177930CCC46EC7D772FE86BEF6F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_DAC2DA35B4E5F25573CE772FE86BA5CA" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7D18D177930CCC46EC7D772FE86BEF6F" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_OpenwaveMessagingMember" xlink:label="loc_sncr_OpenwaveMessagingMember_2B8B6B4CD09B5CC8F277772FE86B9847" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7D18D177930CCC46EC7D772FE86BEF6F" xlink:to="loc_sncr_OpenwaveMessagingMember_2B8B6B4CD09B5CC8F277772FE86B9847" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_C702B41BFF7B76785B13772FE86C76EB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6FC6821702A32EA91527772FE86B1397" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_C702B41BFF7B76785B13772FE86C76EB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C4A8E5302637BFDD5261772FE86C6CC9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_C702B41BFF7B76785B13772FE86C76EB" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C4A8E5302637BFDD5261772FE86C6CC9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C4A8E5302637BFDD5261772FE86C6CC9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_C702B41BFF7B76785B13772FE86C76EB" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C4A8E5302637BFDD5261772FE86C6CC9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaap_TradeNamesMember_8C3337C2314CA3076A96772FE86C9E4B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C4A8E5302637BFDD5261772FE86C6CC9" xlink:to="loc_us-gaap_TradeNamesMember_8C3337C2314CA3076A96772FE86C9E4B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_AD5417492D707892C70E772FE86CDBC2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C4A8E5302637BFDD5261772FE86C6CC9" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_AD5417492D707892C70E772FE86CDBC2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_D2A9914B5C3E61C5F012772FE86C2175" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C4A8E5302637BFDD5261772FE86C6CC9" xlink:to="loc_us-gaap_CustomerRelationshipsMember_D2A9914B5C3E61C5F012772FE86C2175" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_51F5892DE165008EEB50772FE86CAF06" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6FC6821702A32EA91527772FE86B1397" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_51F5892DE165008EEB50772FE86CAF06" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_A4D53E2DB51C82AF5EAD772FE86CA87F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_51F5892DE165008EEB50772FE86CAF06" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_A4D53E2DB51C82AF5EAD772FE86CA87F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_A4D53E2DB51C82AF5EAD772FE86CA87F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_51F5892DE165008EEB50772FE86CAF06" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_A4D53E2DB51C82AF5EAD772FE86CA87F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_A9299353A55F55F6F4EE772FE86C1E91" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_A4D53E2DB51C82AF5EAD772FE86CA87F" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_A9299353A55F55F6F4EE772FE86C1E91" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredAbstract" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_C148692AD2C578DDE405772FE86C3B9D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_F55C5C6351C2FF87406D772FE86C31DB" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_C148692AD2C578DDE405772FE86C3B9D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_29C3962475F92AE4AF9D772FE86CFEC7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_C148692AD2C578DDE405772FE86C3B9D" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_29C3962475F92AE4AF9D772FE86CFEC7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_BA70CA38C0D6383BA6ED772FE86C562A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_C148692AD2C578DDE405772FE86C3B9D" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_BA70CA38C0D6383BA6ED772FE86C562A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_53875142D4814E4E1250772FE86C22A6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_C148692AD2C578DDE405772FE86C3B9D" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_53875142D4814E4E1250772FE86C22A6" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuableAverageMarketValuePeriod" xlink:label="loc_sncr_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuableAverageMarketValuePeriod_9DB298402254A8A0D619772FE86C113E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_C148692AD2C578DDE405772FE86C3B9D" xlink:to="loc_sncr_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuableAverageMarketValuePeriod_9DB298402254A8A0D619772FE86C113E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_F55C5C6351C2FF87406D772FE86C31DB" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_0937961AF9952B1E6BEB772FE86CEBD9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_0937961AF9952B1E6BEB772FE86CEBD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_F54102153D21E4E093B1772FE86DE484" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_F54102153D21E4E093B1772FE86DE484" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_84AA78B1CBEECA27890D772FE86D495A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_84AA78B1CBEECA27890D772FE86D495A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_ABD4877AB1970454D856772FE86DD588" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_ABD4877AB1970454D856772FE86DD588" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_2A4D87533FD234D981BC772FE86D3B94" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_2A4D87533FD234D981BC772FE86D3B94" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_21E2C340D2342A709467772FE86DB180" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_us-gaap_Goodwill_21E2C340D2342A709467772FE86DB180" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill" xlink:label="loc_sncr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill_E544430E2B677FC57FC5772FE86D54AF" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_sncr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill_E544430E2B677FC57FC5772FE86D54AF" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_BusinessAcquisitionPurchasePriceAllocationCurrentLiabilitiesAccountsPayableAndAccruedLiabilities" xlink:label="loc_sncr_BusinessAcquisitionPurchasePriceAllocationCurrentLiabilitiesAccountsPayableAndAccruedLiabilities_AE21580164D00427104F772FE86D099A" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_sncr_BusinessAcquisitionPurchasePriceAllocationCurrentLiabilitiesAccountsPayableAndAccruedLiabilities_AE21580164D00427104F772FE86D099A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_187661B7EF616AC3F65B772FE86D3EB0" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_187661B7EF616AC3F65B772FE86D3EB0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities_41A266B6E410025EE74E772FE86DE7D5" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities_41A266B6E410025EE74E772FE86DE7D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_EB6AA12C21478352CDF9772FE86DAC15" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_EB6AA12C21478352CDF9772FE86DAC15" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_92F08666FBE063511C3F772FE86D164A" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterestAbstract_CBA18C74BADA1C1E23E1772FE86C96CF" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_92F08666FBE063511C3F772FE86D164A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationGoodwillAbstract" xlink:label="loc_us-gaap_BusinessCombinationGoodwillAbstract_4046AC64E75E5FBA477C772FE86D0154" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_F55C5C6351C2FF87406D772FE86C31DB" xlink:to="loc_us-gaap_BusinessCombinationGoodwillAbstract_4046AC64E75E5FBA477C772FE86D0154" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_4EC3D1BBF240135EA7AE772FE86DDF00" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationGoodwillAbstract_4046AC64E75E5FBA477C772FE86D0154" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_4EC3D1BBF240135EA7AE772FE86DDF00" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_8FACF809D9CA3DCE0982772FE86D2A30" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationGoodwillAbstract_4046AC64E75E5FBA477C772FE86D0154" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_8FACF809D9CA3DCE0982772FE86D2A30" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/AcquisitionTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_5ABB8E88D55B1C47683D71241C570623" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_E648258709431F38BAB971241C577F51" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_5ABB8E88D55B1C47683D71241C570623" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_E648258709431F38BAB971241C577F51" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_3475AFC4F0869199CAFA71241C571922" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_E648258709431F38BAB971241C577F51" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_3475AFC4F0869199CAFA71241C571922" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_F7B1D1EAD3AD266CABD171241C575FC0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3475AFC4F0869199CAFA71241C571922" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_F7B1D1EAD3AD266CABD171241C575FC0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_F7B1D1EAD3AD266CABD171241C575FC0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3475AFC4F0869199CAFA71241C571922" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_F7B1D1EAD3AD266CABD171241C575FC0" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_OpenwaveMessagingMember" xlink:label="loc_sncr_OpenwaveMessagingMember_EAAFE9A166220C9F2DDD71241C57DE24" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_F7B1D1EAD3AD266CABD171241C575FC0" xlink:to="loc_sncr_OpenwaveMessagingMember_EAAFE9A166220C9F2DDD71241C57DE24" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_24081947406CCE64250771241C57354B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_5ABB8E88D55B1C47683D71241C570623" xlink:to="loc_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_24081947406CCE64250771241C57354B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/BasisOfPresentationAndConsolidation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/BasisOfPresentationAndConsolidationEarlyAdoptionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems" xlink:label="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementEarlyAdoptionTable" xlink:label="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionTable_1B3AF348540EF274BF1E35D517C65987" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:to="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionTable_1B3AF348540EF274BF1E35D517C65987" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_AF135B420D12F337EA3035D517C6B84B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionTable_1B3AF348540EF274BF1E35D517C65987" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_AF135B420D12F337EA3035D517C6B84B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_ABC9116E9ECBEA363A9F35D517C61430_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_AF135B420D12F337EA3035D517C6B84B" xlink:to="loc_us-gaap_TypeOfAdoptionMember_ABC9116E9ECBEA363A9F35D517C61430_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_ABC9116E9ECBEA363A9F35D517C61430" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_AF135B420D12F337EA3035D517C6B84B" xlink:to="loc_us-gaap_TypeOfAdoptionMember_ABC9116E9ECBEA363A9F35D517C61430" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_AccountingStandardsUpdate201609Member" xlink:label="loc_sncr_AccountingStandardsUpdate201609Member_D69032000A14DBFD926C35D517C653E5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_ABC9116E9ECBEA363A9F35D517C61430" xlink:to="loc_sncr_AccountingStandardsUpdate201609Member_D69032000A14DBFD926C35D517C653E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:label="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_9A42630ECB6916F486D835D517C6E1CC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionTable_1B3AF348540EF274BF1E35D517C65987" xlink:to="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_9A42630ECB6916F486D835D517C6E1CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_91A876D5375FF239B05A35D517C70B92_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_9A42630ECB6916F486D835D517C6E1CC" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_91A876D5375FF239B05A35D517C70B92_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_91A876D5375FF239B05A35D517C70B92" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_9A42630ECB6916F486D835D517C6E1CC" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_91A876D5375FF239B05A35D517C70B92" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_StockCompensationExpenseForfeitureRateMember" xlink:label="loc_sncr_StockCompensationExpenseForfeitureRateMember_8EC3B0C80C4E5610A96B35D517C782F5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingPrincipleMember_91A876D5375FF239B05A35D517C70B92" xlink:to="loc_sncr_StockCompensationExpenseForfeitureRateMember_8EC3B0C80C4E5610A96B35D517C782F5" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_ExcessTaxBenefitsMember" xlink:label="loc_sncr_ExcessTaxBenefitsMember_FA1EBA4055DE05C3ED6235D517C74076" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingPrincipleMember_91A876D5375FF239B05A35D517C70B92" xlink:to="loc_sncr_ExcessTaxBenefitsMember_FA1EBA4055DE05C3ED6235D517C74076" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_TaxWithholdingForShareBasedCompensationMember" xlink:label="loc_sncr_TaxWithholdingForShareBasedCompensationMember_7301039D0818E02DAEEC35D517CCE12B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingPrincipleMember_91A876D5375FF239B05A35D517C70B92" xlink:to="loc_sncr_TaxWithholdingForShareBasedCompensationMember_7301039D0818E02DAEEC35D517CCE12B" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_DeferredTaxAssetsMember" xlink:label="loc_sncr_DeferredTaxAssetsMember_4DDFE39CDF8380948B0A35D517CC0766" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingPrincipleMember_91A876D5375FF239B05A35D517C70B92" xlink:to="loc_sncr_DeferredTaxAssetsMember_4DDFE39CDF8380948B0A35D517CC0766" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_24EF9A2613E7375D184B35D517CC5972" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionTable_1B3AF348540EF274BF1E35D517C65987" xlink:to="loc_us-gaap_StatementScenarioAxis_24EF9A2613E7375D184B35D517CC5972" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_28A8DC7CBB4D11EC424835D517CCDBC2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_24EF9A2613E7375D184B35D517CC5972" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_28A8DC7CBB4D11EC424835D517CCDBC2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_28A8DC7CBB4D11EC424835D517CCDBC2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_24EF9A2613E7375D184B35D517CC5972" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_28A8DC7CBB4D11EC424835D517CCDBC2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioPreviouslyReportedMember" xlink:label="loc_us-gaap_ScenarioPreviouslyReportedMember_6C56158B84115857E50235D517CDD40C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_28A8DC7CBB4D11EC424835D517CCDBC2" xlink:to="loc_us-gaap_ScenarioPreviouslyReportedMember_6C56158B84115857E50235D517CDD40C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementEarlyAdoptionAxis" xlink:label="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_E666EB66C2FB77EFE10F35D517CDDA7B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionTable_1B3AF348540EF274BF1E35D517C65987" xlink:to="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_E666EB66C2FB77EFE10F35D517CDDA7B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPrinciplesEarlyAdoptionMember" xlink:label="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_06E3D5EB63711A42609A35D517CDDA21_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_E666EB66C2FB77EFE10F35D517CDDA7B" xlink:to="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_06E3D5EB63711A42609A35D517CDDA21_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPrinciplesEarlyAdoptionMember" xlink:label="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_06E3D5EB63711A42609A35D517CDDA21" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_E666EB66C2FB77EFE10F35D517CDDA7B" xlink:to="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_06E3D5EB63711A42609A35D517CDDA21" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementEarlyAdoptionEffectMember" xlink:label="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionEffectMember_7BD83764913ED9C765E135D517CD9059" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_06E3D5EB63711A42609A35D517CDDA21" xlink:to="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionEffectMember_7BD83764913ED9C765E135D517CD9059" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption" xlink:label="loc_us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption_4B21B3EDD510015908A635D517CD5010" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:to="loc_us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption_4B21B3EDD510015908A635D517CD5010" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_E970D40B41C58CD5683435D517CE08C1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_E970D40B41C58CD5683435D517CE08C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_772813C41C7BC6CF114B35D517CE6D6C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_772813C41C7BC6CF114B35D517CE6D6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_0F29895E5AF07130B0FE35D517CE23E1" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_0F29895E5AF07130B0FE35D517CE23E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_28FE884D8184C3FCFD6535D517CE915B" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_28FE884D8184C3FCFD6535D517CE915B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_B351FDCA99E8F9CBDA6535D517CEF075" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_B351FDCA99E8F9CBDA6535D517CEF075" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent_68F53BC0ECA6DA41E8E035D517CE9F81" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent_68F53BC0ECA6DA41E8E035D517CE9F81" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_F1DA40E5A91386AF359535D517CEF923" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_F1DA40E5A91386AF359535D517CEF923" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_B89F8072499F1CA4465735D517CE5AEF" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_72C40749CBA97FB43EB735D517CD8753" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_B89F8072499F1CA4465735D517CE5AEF" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/BasisOfPresentationAndConsolidationNewAccountingPronouncementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_E0E3CDECA8273A4DCA16FDCF9843B27D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_DDABFFFCFF516250FD8AFDCF98426954" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_E0E3CDECA8273A4DCA16FDCF9843B27D" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_DDABFFFCFF516250FD8AFDCF98426954" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_E859F92A3FCC97355F37FDCF98423571" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_DDABFFFCFF516250FD8AFDCF98426954" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_E859F92A3FCC97355F37FDCF98423571" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_74055B6230131235940AFDCF9842A51A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_E859F92A3FCC97355F37FDCF98423571" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_74055B6230131235940AFDCF9842A51A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_74055B6230131235940AFDCF9842A51A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_E859F92A3FCC97355F37FDCF98423571" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_74055B6230131235940AFDCF9842A51A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherAssetsMember" xlink:label="loc_us-gaap_OtherAssetsMember_A579DE7123C8B16CE86DFDCF9842373D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_74055B6230131235940AFDCF9842A51A" xlink:to="loc_us-gaap_OtherAssetsMember_A579DE7123C8B16CE86DFDCF9842373D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongTermDebtMember" xlink:label="loc_us-gaap_LongTermDebtMember_2E41886775063D0496E8FDCF98424959" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_74055B6230131235940AFDCF9842A51A" xlink:to="loc_us-gaap_LongTermDebtMember_2E41886775063D0496E8FDCF98424959" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_62E4ABA025A970FB29D2FDCF98421318" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_DDABFFFCFF516250FD8AFDCF98426954" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_62E4ABA025A970FB29D2FDCF98421318" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_A06A7C2DCFE95A376687FDCF98434145_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_62E4ABA025A970FB29D2FDCF98421318" xlink:to="loc_us-gaap_TypeOfAdoptionMember_A06A7C2DCFE95A376687FDCF98434145_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_A06A7C2DCFE95A376687FDCF98434145" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_62E4ABA025A970FB29D2FDCF98421318" xlink:to="loc_us-gaap_TypeOfAdoptionMember_A06A7C2DCFE95A376687FDCF98434145" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_AccountingStandardsUpdate201503Member" xlink:label="loc_sncr_AccountingStandardsUpdate201503Member_0BED73A085866A4A6AFEFDCF98434F15" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_A06A7C2DCFE95A376687FDCF98434145" xlink:to="loc_sncr_AccountingStandardsUpdate201503Member_0BED73A085866A4A6AFEFDCF98434F15" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredFinanceCostsNet" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_D1EF2B57D672A1B609E0FDD1C7641417" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_E0E3CDECA8273A4DCA16FDCF9843B27D" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_D1EF2B57D672A1B609E0FDD1C7641417" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/BasisOfPresentationAndConsolidationPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/BasisOfPresentationAndConsolidationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/CondensedConsolidatedStatementsOfIncomeAndComprehensiveIncomeUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/Debt" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/DebtConvertibleSeniorNotesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_13915E96E46FCEFB2310070536F702C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_us-gaap_DebtInstrumentTable_13915E96E46FCEFB2310070536F702C0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_D8464CEF3C5E9E8B041D070536F75425" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_13915E96E46FCEFB2310070536F702C0" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_D8464CEF3C5E9E8B041D070536F75425" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_427933737D290CCD925B070536F7C9F5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_D8464CEF3C5E9E8B041D070536F75425" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_427933737D290CCD925B070536F7C9F5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_427933737D290CCD925B070536F7C9F5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_D8464CEF3C5E9E8B041D070536F75425" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_427933737D290CCD925B070536F7C9F5" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_ConvertibleSeniorNotesDue2019Member" xlink:label="loc_sncr_ConvertibleSeniorNotesDue2019Member_491289E62ECF742A9294070536F77A13" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_427933737D290CCD925B070536F7C9F5" xlink:to="loc_sncr_ConvertibleSeniorNotesDue2019Member_491289E62ECF742A9294070536F77A13" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_BB2995F5E3C392FB7ED5070536F7F016" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_BB2995F5E3C392FB7ED5070536F7F016" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_B4516702E8133BC25214070536F73FFF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_B4516702E8133BC25214070536F73FFF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_D48D9030EC7F7F97B158070536F76C4A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_D48D9030EC7F7F97B158070536F76C4A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_86FBAA2E981C7CDA76B2070536F7F7C1" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_86FBAA2E981C7CDA76B2070536F7F7C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentConvertibleConversionRatio1" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_3C6A39E098F7EF4ED40B070536F78CE6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_3C6A39E098F7EF4ED40B070536F78CE6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_760F69D15AB77CCBB36C070536F77D2D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_760F69D15AB77CCBB36C070536F77D2D" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_DebtInstrumentRepurchasePriceAsPercentageOfPrincipalAmountRepurchased" xlink:label="loc_sncr_DebtInstrumentRepurchasePriceAsPercentageOfPrincipalAmountRepurchased_D387619E73DF2B80AC1A070536F7C377" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_sncr_DebtInstrumentRepurchasePriceAsPercentageOfPrincipalAmountRepurchased_D387619E73DF2B80AC1A070536F7C377" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_D21A40EC0D5D3CEFD616070536F7293D" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_D21A40EC0D5D3CEFD616070536F7293D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongTermDebtFairValue" xlink:label="loc_us-gaap_LongTermDebtFairValue_BF4BC8557831FCDC84A9070536F8EBB1" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_us-gaap_LongTermDebtFairValue_BF4BC8557831FCDC84A9070536F8EBB1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestExpenseDebt" xlink:label="loc_us-gaap_InterestExpenseDebt_833B41E6335D765A6EEC070536F8CD2A" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3C53BA0E0746816D734A070536F7926F" xlink:to="loc_us-gaap_InterestExpenseDebt_833B41E6335D765A6EEC070536F8CD2A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/DebtCreditFacilityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_D8DF9EB798D42A2DFA0E44E54E08FF79" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_92402A903EC523752C1B44E54E07F04D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_D8DF9EB798D42A2DFA0E44E54E08FF79" xlink:to="loc_us-gaap_DebtInstrumentTable_92402A903EC523752C1B44E54E07F04D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_EA311B5A80B76E1C42DE44E54E0779E1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_92402A903EC523752C1B44E54E07F04D" xlink:to="loc_us-gaap_CreditFacilityAxis_EA311B5A80B76E1C42DE44E54E0779E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_9F241D73F3AE066A3C9944E54E076B45_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_EA311B5A80B76E1C42DE44E54E0779E1" xlink:to="loc_us-gaap_CreditFacilityDomain_9F241D73F3AE066A3C9944E54E076B45_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_9F241D73F3AE066A3C9944E54E076B45" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_EA311B5A80B76E1C42DE44E54E0779E1" xlink:to="loc_us-gaap_CreditFacilityDomain_9F241D73F3AE066A3C9944E54E076B45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_0396ED4B7CD97520E03A44E54E070934" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_9F241D73F3AE066A3C9944E54E076B45" xlink:to="loc_us-gaap_LineOfCreditMember_0396ED4B7CD97520E03A44E54E070934" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_AmendedAndRestatedCreditAgreementMember" xlink:label="loc_sncr_AmendedAndRestatedCreditAgreementMember_710A1DE4FB8441F556AD44E54E0760BE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_9F241D73F3AE066A3C9944E54E076B45" xlink:to="loc_sncr_AmendedAndRestatedCreditAgreementMember_710A1DE4FB8441F556AD44E54E0760BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_A621D857194A3705F03844E54E082D43" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_92402A903EC523752C1B44E54E07F04D" xlink:to="loc_us-gaap_RangeAxis_A621D857194A3705F03844E54E082D43" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_1A40BAEF996FDEF56D6B44E54E089519_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_A621D857194A3705F03844E54E082D43" xlink:to="loc_us-gaap_RangeMember_1A40BAEF996FDEF56D6B44E54E089519_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_1A40BAEF996FDEF56D6B44E54E089519" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_A621D857194A3705F03844E54E082D43" xlink:to="loc_us-gaap_RangeMember_1A40BAEF996FDEF56D6B44E54E089519" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_03CDD6E9ADE18217D2FC44E54E089664" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_1A40BAEF996FDEF56D6B44E54E089519" xlink:to="loc_us-gaap_MinimumMember_03CDD6E9ADE18217D2FC44E54E089664" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_A45173B65D97A10FAE6D44E54E08DA2F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_1A40BAEF996FDEF56D6B44E54E089519" xlink:to="loc_us-gaap_MaximumMember_A45173B65D97A10FAE6D44E54E08DA2F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_1142E5ED2217278CBA6A44E54E08E479" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_92402A903EC523752C1B44E54E07F04D" xlink:to="loc_us-gaap_VariableRateAxis_1142E5ED2217278CBA6A44E54E08E479" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_2F3E7535B981E27152BF44E54E08F9A4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_1142E5ED2217278CBA6A44E54E08E479" xlink:to="loc_us-gaap_VariableRateDomain_2F3E7535B981E27152BF44E54E08F9A4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_2F3E7535B981E27152BF44E54E08F9A4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_1142E5ED2217278CBA6A44E54E08E479" xlink:to="loc_us-gaap_VariableRateDomain_2F3E7535B981E27152BF44E54E08F9A4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_58FE2DD3CCB3B9EF5C2344E54E0874C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_2F3E7535B981E27152BF44E54E08F9A4" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_58FE2DD3CCB3B9EF5C2344E54E0874C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_AA1BE46172C7C4F6F08C44E54E08B6B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_D8DF9EB798D42A2DFA0E44E54E08FF79" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_AA1BE46172C7C4F6F08C44E54E08B6B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_BF2C0826C8568B52906044E54E08F340" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_D8DF9EB798D42A2DFA0E44E54E08FF79" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_BF2C0826C8568B52906044E54E08F340" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_LineOfCreditFacilityRightToIncreaseMaximumBorrowingCapacityAmount" xlink:label="loc_sncr_LineOfCreditFacilityRightToIncreaseMaximumBorrowingCapacityAmount_B7F5FCB92AC9123BD52A44E54E08A08C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_D8DF9EB798D42A2DFA0E44E54E08FF79" xlink:to="loc_sncr_LineOfCreditFacilityRightToIncreaseMaximumBorrowingCapacityAmount_B7F5FCB92AC9123BD52A44E54E08A08C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_2C44F5DFD7C00BAD8ECA44E54E082AFE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_D8DF9EB798D42A2DFA0E44E54E08FF79" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_2C44F5DFD7C00BAD8ECA44E54E082AFE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortTermBorrowings" xlink:label="loc_us-gaap_ShortTermBorrowings_C179970A27FEAFB11CA344E54E08E57F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_D8DF9EB798D42A2DFA0E44E54E08FF79" xlink:to="loc_us-gaap_ShortTermBorrowings_C179970A27FEAFB11CA344E54E08E57F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityFee" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityFee_10BC157004E0DEA4394144E54E08E6E1" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_D8DF9EB798D42A2DFA0E44E54E08FF79" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityFee_10BC157004E0DEA4394144E54E08E6E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestExpenseDebt" xlink:label="loc_us-gaap_InterestExpenseDebt_6EFFC23EAA2BA7DCA61344E54E08F627" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_D8DF9EB798D42A2DFA0E44E54E08FF79" xlink:to="loc_us-gaap_InterestExpenseDebt_6EFFC23EAA2BA7DCA61344E54E08F627" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/DebtTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/DescriptionOfBusiness" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/EarningsPerCommonShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/EarningsPerCommonShareDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3B22752733394F9B886845BDB2FB0878" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_96BEF26BDC00F0847B9F45BDB2FAF674" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3B22752733394F9B886845BDB2FB0878" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_96BEF26BDC00F0847B9F45BDB2FAF674" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_CCB3F1B54FD816440FFD45BDB2FB9281" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_96BEF26BDC00F0847B9F45BDB2FAF674" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_CCB3F1B54FD816440FFD45BDB2FB9281" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_D5708E8E40384C569D4B45BDB2FB5FA2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_CCB3F1B54FD816440FFD45BDB2FB9281" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_D5708E8E40384C569D4B45BDB2FB5FA2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_D5708E8E40384C569D4B45BDB2FB5FA2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_CCB3F1B54FD816440FFD45BDB2FB9281" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_D5708E8E40384C569D4B45BDB2FB5FA2" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_EmployeeAndDirectorsStockOptionsMember" xlink:label="loc_sncr_EmployeeAndDirectorsStockOptionsMember_05F210A484F2FF95513945BDB2FB111F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_D5708E8E40384C569D4B45BDB2FB5FA2" xlink:to="loc_sncr_EmployeeAndDirectorsStockOptionsMember_05F210A484F2FF95513945BDB2FB111F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EarningsPerShareReconciliationAbstract" xlink:label="loc_us-gaap_EarningsPerShareReconciliationAbstract_A2DA41C7EDE3D2C71D9945BDB2FB1B19" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3B22752733394F9B886845BDB2FB0878" xlink:to="loc_us-gaap_EarningsPerShareReconciliationAbstract_A2DA41C7EDE3D2C71D9945BDB2FB1B19" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_E686029F22D51DC2D7A645BDB2FB17A9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_A2DA41C7EDE3D2C71D9945BDB2FB1B19" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_E686029F22D51DC2D7A645BDB2FB17A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_700EC3F706746638A45245BDB2FB4412" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_E686029F22D51DC2D7A645BDB2FB17A9" xlink:to="loc_us-gaap_NetIncomeLoss_700EC3F706746638A45245BDB2FB4412" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestOnConvertibleDebtNetOfTax" xlink:label="loc_us-gaap_InterestOnConvertibleDebtNetOfTax_2C1A5F6D1D2C05CDC80745BDB2FD9771" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_E686029F22D51DC2D7A645BDB2FB17A9" xlink:to="loc_us-gaap_InterestOnConvertibleDebtNetOfTax_2C1A5F6D1D2C05CDC80745BDB2FD9771" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_AE0ADD42D908C5E86EFD45BDB2FDBE2F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDilutedAbstract_E686029F22D51DC2D7A645BDB2FB17A9" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_AE0ADD42D908C5E86EFD45BDB2FDBE2F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_C3579BAE2D6CC626C4C645BDB2FD4C53" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_A2DA41C7EDE3D2C71D9945BDB2FB1B19" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_C3579BAE2D6CC626C4C645BDB2FD4C53" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_A08A33D44221123E791945BDB2FD823B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_C3579BAE2D6CC626C4C645BDB2FD4C53" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_A08A33D44221123E791945BDB2FD823B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract_3C66F05C3A0A818C8B1245BDB2FDB8AB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_C3579BAE2D6CC626C4C645BDB2FD4C53" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract_3C66F05C3A0A818C8B1245BDB2FDB8AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities_72C79DD5D7BFB5041B3045BDB2FD886A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract_3C66F05C3A0A818C8B1245BDB2FDB8AB" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities_72C79DD5D7BFB5041B3045BDB2FD886A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_52E0B878BF4A66FEBD9545BDB2FD3BD4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract_3C66F05C3A0A818C8B1245BDB2FDB8AB" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_52E0B878BF4A66FEBD9545BDB2FD3BD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_6B0893153C851B0BD15B45BDB2FD2355" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_C3579BAE2D6CC626C4C645BDB2FD4C53" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_6B0893153C851B0BD15B45BDB2FD2355" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_A790B3CDDA52ABDDEBFE45BDB2FE6280" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3B22752733394F9B886845BDB2FB0878" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_A790B3CDDA52ABDDEBFE45BDB2FE6280" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/EarningsPerCommonShareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilities" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesAfsSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_C6E0119C390FB45672776D255F7480CF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_89C41E355D869D74EBE66D255F740E77" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_C6E0119C390FB45672776D255F7480CF" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_89C41E355D869D74EBE66D255F740E77" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsAxis" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_9592E7F010C5421DB0CB6D255F74F19C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_89C41E355D869D74EBE66D255F740E77" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_9592E7F010C5421DB0CB6D255F74F19C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_497293CE987F5DF9E2B36D255F745596_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_9592E7F010C5421DB0CB6D255F74F19C" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_497293CE987F5DF9E2B36D255F745596_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_497293CE987F5DF9E2B36D255F745596" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_9592E7F010C5421DB0CB6D255F74F19C" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_497293CE987F5DF9E2B36D255F745596" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CertificatesOfDepositMember" xlink:label="loc_us-gaap_CertificatesOfDepositMember_953AC2D5D5B9A00FB99E6D255F74A1B6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_497293CE987F5DF9E2B36D255F745596" xlink:to="loc_us-gaap_CertificatesOfDepositMember_953AC2D5D5B9A00FB99E6D255F74A1B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_D0AD2C37523E74E5FAE26D255F7495E2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_89C41E355D869D74EBE66D255F740E77" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_D0AD2C37523E74E5FAE26D255F7495E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_7948C28F2DCA31F117036D255F74C7C2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_D0AD2C37523E74E5FAE26D255F7495E2" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_7948C28F2DCA31F117036D255F74C7C2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_7948C28F2DCA31F117036D255F74C7C2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_D0AD2C37523E74E5FAE26D255F7495E2" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_7948C28F2DCA31F117036D255F74C7C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CorporateBondSecuritiesMember" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_92977CD8AE638CAEB9D06D255F7404DE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_7948C28F2DCA31F117036D255F74C7C2" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_92977CD8AE638CAEB9D06D255F7404DE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MunicipalBondsMember" xlink:label="loc_us-gaap_MunicipalBondsMember_57F0BDF4F51B6B3BEB116D255F743A4E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_7948C28F2DCA31F117036D255F74C7C2" xlink:to="loc_us-gaap_MunicipalBondsMember_57F0BDF4F51B6B3BEB116D255F743A4E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FixedIncomeFundsMember" xlink:label="loc_us-gaap_FixedIncomeFundsMember_D2EC5F85AC4466F756CE6D255F747960" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_7948C28F2DCA31F117036D255F74C7C2" xlink:to="loc_us-gaap_FixedIncomeFundsMember_D2EC5F85AC4466F756CE6D255F747960" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesFairValueToAmortizedCostBasisAbstract" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesFairValueToAmortizedCostBasisAbstract_D6F661B85F8E33EF39286D255F757667" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_C6E0119C390FB45672776D255F7480CF" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesFairValueToAmortizedCostBasisAbstract_D6F661B85F8E33EF39286D255F757667" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAmortizedCost" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_B01FC550D78F82E395966D255F75BD69" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesFairValueToAmortizedCostBasisAbstract_D6F661B85F8E33EF39286D255F757667" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_B01FC550D78F82E395966D255F75BD69" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_F682106A77668DC520596D255F75E30C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesFairValueToAmortizedCostBasisAbstract_D6F661B85F8E33EF39286D255F757667" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_F682106A77668DC520596D255F75E30C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_10C61C0E97F47B6B18D96D255F75C949" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesFairValueToAmortizedCostBasisAbstract_D6F661B85F8E33EF39286D255F757667" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_10C61C0E97F47B6B18D96D255F75C949" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_EFCF8D151A96E42817BE6D255F75B72D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesFairValueToAmortizedCostBasisAbstract_D6F661B85F8E33EF39286D255F757667" xlink:to="loc_us-gaap_AvailableForSaleSecurities_EFCF8D151A96E42817BE6D255F75B72D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesAfsSecuritiesExpectedMaturitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesAfsSecuritiesInUnrealizedLossPositionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_A6DB02270AE0DC9BBF08772FE8E81E8A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_C9BBFE177AC7D18DCCA8772FE8E89899" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_A6DB02270AE0DC9BBF08772FE8E81E8A" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_C9BBFE177AC7D18DCCA8772FE8E89899" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsAxis" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_EDA55BFDF2AAA83F276E772FE8E894D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_C9BBFE177AC7D18DCCA8772FE8E89899" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_EDA55BFDF2AAA83F276E772FE8E894D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_4DAC2A9AE2EE8995EBA9772FE8E8CEF1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_EDA55BFDF2AAA83F276E772FE8E894D8" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_4DAC2A9AE2EE8995EBA9772FE8E8CEF1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_4DAC2A9AE2EE8995EBA9772FE8E8CEF1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_EDA55BFDF2AAA83F276E772FE8E894D8" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_4DAC2A9AE2EE8995EBA9772FE8E8CEF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CertificatesOfDepositMember" xlink:label="loc_us-gaap_CertificatesOfDepositMember_1060705950EC0DD222CF772FE8E87F03" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_4DAC2A9AE2EE8995EBA9772FE8E8CEF1" xlink:to="loc_us-gaap_CertificatesOfDepositMember_1060705950EC0DD222CF772FE8E87F03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_81D704FE6DF3FDD88F94772FE8E8A004" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_C9BBFE177AC7D18DCCA8772FE8E89899" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_81D704FE6DF3FDD88F94772FE8E8A004" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_58D3902BAC6CC79D9877772FE8E8BA1F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_81D704FE6DF3FDD88F94772FE8E8A004" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_58D3902BAC6CC79D9877772FE8E8BA1F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_58D3902BAC6CC79D9877772FE8E8BA1F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_81D704FE6DF3FDD88F94772FE8E8A004" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_58D3902BAC6CC79D9877772FE8E8BA1F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CorporateBondSecuritiesMember" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_FDD98DA2108AFA6FF3D7772FE8E87941" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_58D3902BAC6CC79D9877772FE8E8BA1F" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_FDD98DA2108AFA6FF3D7772FE8E87941" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MunicipalBondsMember" xlink:label="loc_us-gaap_MunicipalBondsMember_463F5BDF6ACB16793230772FE8E81F8C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_58D3902BAC6CC79D9877772FE8E8BA1F" xlink:to="loc_us-gaap_MunicipalBondsMember_463F5BDF6ACB16793230772FE8E81F8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FixedIncomeFundsMember" xlink:label="loc_us-gaap_FixedIncomeFundsMember_EBEC6F608DB083F2855C772FE8E871E4" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_58D3902BAC6CC79D9877772FE8E8BA1F" xlink:to="loc_us-gaap_FixedIncomeFundsMember_EBEC6F608DB083F2855C772FE8E871E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_A5A9142B8319940F4884772FE8E8C084" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_A6DB02270AE0DC9BBF08772FE8E81E8A" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_A5A9142B8319940F4884772FE8E8C084" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_0975F6D79EF075ED7429772FE8E90E0D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_A5A9142B8319940F4884772FE8E8C084" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_0975F6D79EF075ED7429772FE8E90E0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_5D7D50D61FD2C34F9E09772FE8E9F7A8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_A5A9142B8319940F4884772FE8E8C084" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_5D7D50D61FD2C34F9E09772FE8E9F7A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss_34FE73C4C0191C5F9893772FE8E95F98" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_A5A9142B8319940F4884772FE8E8C084" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss_34FE73C4C0191C5F9893772FE8E95F98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_842A466CB177BE961401772FE8E9BBE4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_A6DB02270AE0DC9BBF08772FE8E81E8A" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_842A466CB177BE961401772FE8E9BBE4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_07146AF4F635F46025B1772FE8E9D638" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_842A466CB177BE961401772FE8E9BBE4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_07146AF4F635F46025B1772FE8E9D638" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_4F8FAFDA648338765C24772FE8E9A740" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_842A466CB177BE961401772FE8E9BBE4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_4F8FAFDA648338765C24772FE8E9A740" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_2D2787833A2E5E1DEC1A772FE8E97097" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_842A466CB177BE961401772FE8E9BBE4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_2D2787833A2E5E1DEC1A772FE8E97097" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesHeirarchyDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_D4AE3F23CA45EDEBF7AD711E7ACC8FE4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_B7BA6AC50B48332812F8711E7ACAC9A5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_D4AE3F23CA45EDEBF7AD711E7ACC8FE4" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_B7BA6AC50B48332812F8711E7ACAC9A5" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_668C9B976A921F291ABB711E7ACA89D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_B7BA6AC50B48332812F8711E7ACAC9A5" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_668C9B976A921F291ABB711E7ACA89D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1164B8CD4D7911AAA975711E7ACB0C67_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_668C9B976A921F291ABB711E7ACA89D8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1164B8CD4D7911AAA975711E7ACB0C67_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1164B8CD4D7911AAA975711E7ACB0C67" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_668C9B976A921F291ABB711E7ACA89D8" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1164B8CD4D7911AAA975711E7ACB0C67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_C5F0AE9FA12EBAA7BF94711E7ACB9625" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1164B8CD4D7911AAA975711E7ACB0C67" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_C5F0AE9FA12EBAA7BF94711E7ACB9625" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_810D9C45B9554CFC262A711E7ACBDE04" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1164B8CD4D7911AAA975711E7ACB0C67" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_810D9C45B9554CFC262A711E7ACBDE04" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_075E2B45C6480014B8D5711E7ACB0E20" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1164B8CD4D7911AAA975711E7ACB0C67" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_075E2B45C6480014B8D5711E7ACB0E20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_EA6D72BBDCAD91439604711E7ACB567F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_B7BA6AC50B48332812F8711E7ACAC9A5" xlink:to="loc_dei_LegalEntityAxis_EA6D72BBDCAD91439604711E7ACB567F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_C9D5D61A3F4594F3648B711E7ACBBFD7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_EA6D72BBDCAD91439604711E7ACB567F" xlink:to="loc_dei_EntityDomain_C9D5D61A3F4594F3648B711E7ACBBFD7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_C9D5D61A3F4594F3648B711E7ACBBFD7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_EA6D72BBDCAD91439604711E7ACB567F" xlink:to="loc_dei_EntityDomain_C9D5D61A3F4594F3648B711E7ACBBFD7" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_RedeemableNoncontrollingInterestMember" xlink:label="loc_sncr_RedeemableNoncontrollingInterestMember_B39D72F0CE0DDCEE597B711E7ACBEDC2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_C9D5D61A3F4594F3648B711E7ACBBFD7" xlink:to="loc_sncr_RedeemableNoncontrollingInterestMember_B39D72F0CE0DDCEE597B711E7ACBEDC2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsFairValueDisclosureAbstract" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_7DD3622A8E4527BE44E1711E7ACC6AA1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_D4AE3F23CA45EDEBF7AD711E7ACC8FE4" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_7DD3622A8E4527BE44E1711E7ACC6AA1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_FF7B864A54983F9CE0F8711E7ACC3EB7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_7DD3622A8E4527BE44E1711E7ACC6AA1" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_FF7B864A54983F9CE0F8711E7ACC3EB7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_CDD5D322B3FBBFEA3208711E7ACCA9B8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_7DD3622A8E4527BE44E1711E7ACC6AA1" xlink:to="loc_us-gaap_AvailableForSaleSecurities_CDD5D322B3FBBFEA3208711E7ACCA9B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_3FFDAE43F4008CF49E9F711E7ACC126E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_7DD3622A8E4527BE44E1711E7ACC6AA1" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_3FFDAE43F4008CF49E9F711E7ACC126E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_5D443A7884B4F15F7F75711E7ACC1348" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_D4AE3F23CA45EDEBF7AD711E7ACC8FE4" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_5D443A7884B4F15F7F75711E7ACC1348" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_753DD5D8D3512047419A711E7ACC3D9D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_5D443A7884B4F15F7F75711E7ACC1348" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_753DD5D8D3512047419A711E7ACC3D9D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_3D19237516F5497DD899711E7ACCBF0D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_5D443A7884B4F15F7F75711E7ACC1348" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_3D19237516F5497DD899711E7ACCBF0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisAlternativeAbstract" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisAlternativeAbstract_3682FE3841E0A847BDEE711E7ACC9BEC" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_D4AE3F23CA45EDEBF7AD711E7ACC8FE4" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisAlternativeAbstract_3682FE3841E0A847BDEE711E7ACC9BEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RedeemableNoncontrollingInterestEquityOtherFairValue" xlink:label="loc_us-gaap_RedeemableNoncontrollingInterestEquityOtherFairValue_FF4D0B8D85255192138A711E7ACCD06B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisAlternativeAbstract_3682FE3841E0A847BDEE711E7ACC9BEC" xlink:to="loc_us-gaap_RedeemableNoncontrollingInterestEquityOtherFairValue_FF4D0B8D85255192138A711E7ACCD06B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TemporaryEquityAccretionToRedemptionValue" xlink:label="loc_us-gaap_TemporaryEquityAccretionToRedemptionValue_A6937F4BE88432699CD1711E7ACD7C37" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisAlternativeAbstract_3682FE3841E0A847BDEE711E7ACC9BEC" xlink:to="loc_us-gaap_TemporaryEquityAccretionToRedemptionValue_A6937F4BE88432699CD1711E7ACD7C37" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueTransfersBetweenLevel1AndLevel2DescriptionAndPolicyAbstract" xlink:label="loc_us-gaap_FairValueTransfersBetweenLevel1AndLevel2DescriptionAndPolicyAbstract_90F5274BC1B4695937A3711E7ACD19FD" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_D4AE3F23CA45EDEBF7AD711E7ACC8FE4" xlink:to="loc_us-gaap_FairValueTransfersBetweenLevel1AndLevel2DescriptionAndPolicyAbstract_90F5274BC1B4695937A3711E7ACD19FD" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_FairValueAssetsTransfersBetweenLevels12And3Amount" xlink:label="loc_sncr_FairValueAssetsTransfersBetweenLevels12And3Amount_EDBED00B974929F84756711E7ACD3EF1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueTransfersBetweenLevel1AndLevel2DescriptionAndPolicyAbstract_90F5274BC1B4695937A3711E7ACD19FD" xlink:to="loc_sncr_FairValueAssetsTransfersBetweenLevels12And3Amount_EDBED00B974929F84756711E7ACD3EF1" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesLevel3ContingentConsiderationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_9F2C6AB788A123409B85711E82975834" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_F31FD0FF56753481BD08711E8296FDAD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_9F2C6AB788A123409B85711E82975834" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_F31FD0FF56753481BD08711E8296FDAD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_A2FEAEEFB9481BC809D9711E82968978" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_F31FD0FF56753481BD08711E8296FDAD" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_A2FEAEEFB9481BC809D9711E82968978" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_16781396EA04E15F03B2711E82974778_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_A2FEAEEFB9481BC809D9711E82968978" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_16781396EA04E15F03B2711E82974778_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_16781396EA04E15F03B2711E82974778" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_A2FEAEEFB9481BC809D9711E82968978" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_16781396EA04E15F03B2711E82974778" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_E2C8FC70682F07F416D2711E82973C76" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_16781396EA04E15F03B2711E82974778" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_E2C8FC70682F07F416D2711E82973C76" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_E6CA3D4AA83E0060B0B1711E8297C8FB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_F31FD0FF56753481BD08711E8296FDAD" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_E6CA3D4AA83E0060B0B1711E8297C8FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_795AE30E3D9B9840EA3E711E82975900_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_E6CA3D4AA83E0060B0B1711E8297C8FB" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_795AE30E3D9B9840EA3E711E82975900_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_795AE30E3D9B9840EA3E711E82975900" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_E6CA3D4AA83E0060B0B1711E8297C8FB" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_795AE30E3D9B9840EA3E711E82975900" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommitmentsMember" xlink:label="loc_us-gaap_CommitmentsMember_326CC47A1BA350AD8D8A711E829758C9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_795AE30E3D9B9840EA3E711E82975900" xlink:to="loc_us-gaap_CommitmentsMember_326CC47A1BA350AD8D8A711E829758C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_4D816273491AD4B96D21711E82976B7C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_9F2C6AB788A123409B85711E82975834" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_4D816273491AD4B96D21711E82976B7C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_D56643733B600BFB7551711E82975D2E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_4D816273491AD4B96D21711E82976B7C" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_D56643733B600BFB7551711E82975D2E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_3F7E380755D00F9DA97A711E829709C2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_4D816273491AD4B96D21711E82976B7C" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_3F7E380755D00F9DA97A711E829709C2" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesLevel3RedeemableNoncontrollingInterestsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_BF4502B45B539F6F80EA711E81B6FC0F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_942F60A893403E1C6970711E81B679D4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_BF4502B45B539F6F80EA711E81B6FC0F" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_942F60A893403E1C6970711E81B679D4" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_B272DD946A392A3DFB70711E81B6A100" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_942F60A893403E1C6970711E81B679D4" xlink:to="loc_dei_LegalEntityAxis_B272DD946A392A3DFB70711E81B6A100" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_EC02595238DC78750D84711E81B607EE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_B272DD946A392A3DFB70711E81B6A100" xlink:to="loc_dei_EntityDomain_EC02595238DC78750D84711E81B607EE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_EC02595238DC78750D84711E81B607EE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_B272DD946A392A3DFB70711E81B6A100" xlink:to="loc_dei_EntityDomain_EC02595238DC78750D84711E81B607EE" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_RedeemableNoncontrollingInterestMember" xlink:label="loc_sncr_RedeemableNoncontrollingInterestMember_E36616AE0B30F260CC83711E81B64FF0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_EC02595238DC78750D84711E81B607EE" xlink:to="loc_sncr_RedeemableNoncontrollingInterestMember_E36616AE0B30F260CC83711E81B64FF0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_5D28F9DD497F24DCE75E711E81B6D613" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_BF4502B45B539F6F80EA711E81B6FC0F" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_5D28F9DD497F24DCE75E711E81B6D613" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_B46E3A5761A87C3CF598711E81B6FF5C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_5D28F9DD497F24DCE75E711E81B6D613" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_B46E3A5761A87C3CF598711E81B6FF5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TemporaryEquityAccretionToRedemptionValue" xlink:label="loc_us-gaap_TemporaryEquityAccretionToRedemptionValue_B98F506FFE9B025BDAA7711E81B6EAB8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_5D28F9DD497F24DCE75E711E81B6D613" xlink:to="loc_us-gaap_TemporaryEquityAccretionToRedemptionValue_B98F506FFE9B025BDAA7711E81B6EAB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_DC1BECBAF52E39BA41E1711E81B6FDE9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_5D28F9DD497F24DCE75E711E81B6D613" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_DC1BECBAF52E39BA41E1711E81B6FDE9" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/FairValueMeasurementsOfAssetsAndLiabilitiesTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_B8A1BFC312A09D43E734BDDD2B38FC08" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_B92D1CFA592913B49737BDDD2B37D431" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_B8A1BFC312A09D43E734BDDD2B38FC08" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_B92D1CFA592913B49737BDDD2B37D431" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_B8D1C6C9CC26045147ADBDDD2B371208" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_B92D1CFA592913B49737BDDD2B37D431" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_B8D1C6C9CC26045147ADBDDD2B371208" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_A08B4DDDDA9FEB7D7EB6BDDD2B379014_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_B8D1C6C9CC26045147ADBDDD2B371208" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_A08B4DDDDA9FEB7D7EB6BDDD2B379014_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_A08B4DDDDA9FEB7D7EB6BDDD2B379014" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_B8D1C6C9CC26045147ADBDDD2B371208" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_A08B4DDDDA9FEB7D7EB6BDDD2B379014" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommitmentsMember" xlink:label="loc_us-gaap_CommitmentsMember_B75760855B2A9815CE26BDDD2B376353" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_A08B4DDDDA9FEB7D7EB6BDDD2B379014" xlink:to="loc_us-gaap_CommitmentsMember_B75760855B2A9815CE26BDDD2B376353" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_9DDA11ED656054F24D82BDDD2B3739E8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_B92D1CFA592913B49737BDDD2B37D431" xlink:to="loc_dei_LegalEntityAxis_9DDA11ED656054F24D82BDDD2B3739E8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_27529CC5826D750C026CBDDD2B37B37C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_9DDA11ED656054F24D82BDDD2B3739E8" xlink:to="loc_dei_EntityDomain_27529CC5826D750C026CBDDD2B37B37C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_27529CC5826D750C026CBDDD2B37B37C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_9DDA11ED656054F24D82BDDD2B3739E8" xlink:to="loc_dei_EntityDomain_27529CC5826D750C026CBDDD2B37B37C" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_RedeemableNoncontrollingInterestMember" xlink:label="loc_sncr_RedeemableNoncontrollingInterestMember_6F01A63087CEC41C1844BDDD2B37ADF5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_27529CC5826D750C026CBDDD2B37B37C" xlink:to="loc_sncr_RedeemableNoncontrollingInterestMember_6F01A63087CEC41C1844BDDD2B37ADF5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_7C50E5FABF3968188E5EBDDD2B38971B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_B8A1BFC312A09D43E734BDDD2B38FC08" xlink:to="loc_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_7C50E5FABF3968188E5EBDDD2B38971B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock_26E8E245641A7010CB18BDDD2B3817B3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_B8A1BFC312A09D43E734BDDD2B38FC08" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock_26E8E245641A7010CB18BDDD2B3817B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueTableTextBlock" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueTableTextBlock_0A4B9739CE0FC34633CABDDD2B385B14" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_B8A1BFC312A09D43E734BDDD2B38FC08" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueTableTextBlock_0A4B9739CE0FC34633CABDDD2B385B14" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentsClassifiedByContractualMaturityDateTableTextBlock" xlink:label="loc_us-gaap_InvestmentsClassifiedByContractualMaturityDateTableTextBlock_F409A18C788AD4FF620BBDDD2B38E7EA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_B8A1BFC312A09D43E734BDDD2B38FC08" xlink:to="loc_us-gaap_InvestmentsClassifiedByContractualMaturityDateTableTextBlock_F409A18C788AD4FF620BBDDD2B38E7EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_A1ECE749410778FD6E95BDDD2B3806DB" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_B8A1BFC312A09D43E734BDDD2B38FC08" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_A1ECE749410778FD6E95BDDD2B3806DB" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/GoodwillAndIntangibles" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/GoodwillAndIntangiblesGoodwillDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/GoodwillAndIntangiblesIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_927F105BC822F1A296562108E35A367E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_DD5C6CB9C160572A5E3A2108E358B4BE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_927F105BC822F1A296562108E35A367E" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_DD5C6CB9C160572A5E3A2108E358B4BE" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4EDAD6576E5554067F1A2108E358D26A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_DD5C6CB9C160572A5E3A2108E358B4BE" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4EDAD6576E5554067F1A2108E358D26A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_91C39FA5C128993F1B082108E358F868_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4EDAD6576E5554067F1A2108E358D26A" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_91C39FA5C128993F1B082108E358F868_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_91C39FA5C128993F1B082108E358F868" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4EDAD6576E5554067F1A2108E358D26A" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_91C39FA5C128993F1B082108E358F868" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaap_TradeNamesMember_F1F21EF374CBE140FB562108E3584957" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_91C39FA5C128993F1B082108E358F868" xlink:to="loc_us-gaap_TradeNamesMember_F1F21EF374CBE140FB562108E3584957" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_2F09BA16368E9C3C18642108E358E9A2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_91C39FA5C128993F1B082108E358F868" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_2F09BA16368E9C3C18642108E358E9A2" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_CustomerListsAndRelationshipsMember" xlink:label="loc_sncr_CustomerListsAndRelationshipsMember_71D9F9BFCC5132CE098B2108E3583773" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_91C39FA5C128993F1B082108E358F868" xlink:to="loc_sncr_CustomerListsAndRelationshipsMember_71D9F9BFCC5132CE098B2108E3583773" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_CapitalizedSoftwareAndPatentsMember" xlink:label="loc_sncr_CapitalizedSoftwareAndPatentsMember_5BC53FC041D0D3F4BA3B2108E35A8E3B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_91C39FA5C128993F1B082108E358F868" xlink:to="loc_sncr_CapitalizedSoftwareAndPatentsMember_5BC53FC041D0D3F4BA3B2108E35A8E3B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_825B9A34C04FF61930D82108E35A6B63" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_927F105BC822F1A296562108E35A367E" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_825B9A34C04FF61930D82108E35A6B63" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNetAbstract" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_C8B8370B6638349C787E2108E35AFABB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_927F105BC822F1A296562108E35A367E" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_C8B8370B6638349C787E2108E35AFABB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_DF78594E85D5AC42942C2108E35AF39E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_C8B8370B6638349C787E2108E35AFABB" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_DF78594E85D5AC42942C2108E35AF39E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_C999327DBC4F7525E38F2108E35B810D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_C8B8370B6638349C787E2108E35AFABB" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_C999327DBC4F7525E38F2108E35B810D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_B4E86AFEEFDE562F4C162108E35BBBD2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_C8B8370B6638349C787E2108E35AFABB" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_B4E86AFEEFDE562F4C162108E35BBBD2" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/GoodwillAndIntangiblesIntangibleAssetsFutureAmortizationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/GoodwillAndIntangiblesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems" xlink:label="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_CC143BFF24E93992BA4725862BBD10B4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementEarlyAdoptionTable" xlink:label="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionTable_E628E44F4D4D3CC0EDD325862BBB2B21" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_CC143BFF24E93992BA4725862BBD10B4" xlink:to="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionTable_E628E44F4D4D3CC0EDD325862BBB2B21" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_59C468E136085630405925862BBC85EB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionTable_E628E44F4D4D3CC0EDD325862BBB2B21" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_59C468E136085630405925862BBC85EB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_1D9C15EFD6861C430FB025862BBCDEA5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_59C468E136085630405925862BBC85EB" xlink:to="loc_us-gaap_TypeOfAdoptionMember_1D9C15EFD6861C430FB025862BBCDEA5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_1D9C15EFD6861C430FB025862BBCDEA5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_59C468E136085630405925862BBC85EB" xlink:to="loc_us-gaap_TypeOfAdoptionMember_1D9C15EFD6861C430FB025862BBCDEA5" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_AccountingStandardsUpdate201609Member" xlink:label="loc_sncr_AccountingStandardsUpdate201609Member_A265844E9EEE48EFB85325862BBD730E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_1D9C15EFD6861C430FB025862BBCDEA5" xlink:to="loc_sncr_AccountingStandardsUpdate201609Member_A265844E9EEE48EFB85325862BBD730E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementEarlyAdoptionAxis" xlink:label="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_B4CE6FF1A5018999DD3A25862BBD77AC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionTable_E628E44F4D4D3CC0EDD325862BBB2B21" xlink:to="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_B4CE6FF1A5018999DD3A25862BBD77AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPrinciplesEarlyAdoptionMember" xlink:label="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_97AE3A0E1A47F8B2741425862BBD0E58_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_B4CE6FF1A5018999DD3A25862BBD77AC" xlink:to="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_97AE3A0E1A47F8B2741425862BBD0E58_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPrinciplesEarlyAdoptionMember" xlink:label="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_97AE3A0E1A47F8B2741425862BBD0E58" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_B4CE6FF1A5018999DD3A25862BBD77AC" xlink:to="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_97AE3A0E1A47F8B2741425862BBD0E58" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NewAccountingPronouncementEarlyAdoptionEffectMember" xlink:label="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionEffectMember_C94FA99B30F5C78E5B4D25862BBD6F97" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_97AE3A0E1A47F8B2741425862BBD0E58" xlink:to="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionEffectMember_C94FA99B30F5C78E5B4D25862BBD6F97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_1FA77725AC61840EC99825862BBD9771" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionLineItems_CC143BFF24E93992BA4725862BBD10B4" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_1FA77725AC61840EC99825862BBD9771" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_49F8AE3DF8A3BDA1669F25862BBDA460" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_1FA77725AC61840EC99825862BBD9771" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_49F8AE3DF8A3BDA1669F25862BBDA460" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_3B588049F78741A063D625862BBED199" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_1FA77725AC61840EC99825862BBD9771" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_3B588049F78741A063D625862BBED199" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_E9EDE6D6CEC0190A5DA125862BBEBF16" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_1FA77725AC61840EC99825862BBD9771" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_E9EDE6D6CEC0190A5DA125862BBEBF16" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/LegalMatters" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/LegalMattersDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_4FDB5625CD3E47DC2C2D2AC924AA05F1" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_149E105FA636612983972AC924A91FF6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_4FDB5625CD3E47DC2C2D2AC924AA05F1" xlink:to="loc_us-gaap_LossContingenciesTable_149E105FA636612983972AC924A91FF6" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ContingentConsiderationByTypeAxis" xlink:label="loc_us-gaap_ContingentConsiderationByTypeAxis_8CE4437F756ED656C6A92AC924A9A44D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_149E105FA636612983972AC924A91FF6" xlink:to="loc_us-gaap_ContingentConsiderationByTypeAxis_8CE4437F756ED656C6A92AC924A9A44D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ContingentConsiderationTypeDomain" xlink:label="loc_us-gaap_ContingentConsiderationTypeDomain_16E475C00D93ACB3FAE82AC924A932BB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContingentConsiderationByTypeAxis_8CE4437F756ED656C6A92AC924A9A44D" xlink:to="loc_us-gaap_ContingentConsiderationTypeDomain_16E475C00D93ACB3FAE82AC924A932BB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ContingentConsiderationTypeDomain" xlink:label="loc_us-gaap_ContingentConsiderationTypeDomain_16E475C00D93ACB3FAE82AC924A932BB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContingentConsiderationByTypeAxis_8CE4437F756ED656C6A92AC924A9A44D" xlink:to="loc_us-gaap_ContingentConsiderationTypeDomain_16E475C00D93ACB3FAE82AC924A932BB" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_ObligationsUnderAcquisitionAgreementMember" xlink:label="loc_sncr_ObligationsUnderAcquisitionAgreementMember_66D3CEEAF783776CE42E2AC924A95281" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContingentConsiderationTypeDomain_16E475C00D93ACB3FAE82AC924A932BB" xlink:to="loc_sncr_ObligationsUnderAcquisitionAgreementMember_66D3CEEAF783776CE42E2AC924A95281" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_8FA3F1BF94B9EF5E0D472AC924A9EDAC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_149E105FA636612983972AC924A91FF6" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_8FA3F1BF94B9EF5E0D472AC924A9EDAC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ABF4A9939D359E810E8F2AC924A90DAA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_8FA3F1BF94B9EF5E0D472AC924A9EDAC" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ABF4A9939D359E810E8F2AC924A90DAA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ABF4A9939D359E810E8F2AC924A90DAA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_8FA3F1BF94B9EF5E0D472AC924A9EDAC" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ABF4A9939D359E810E8F2AC924A90DAA" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_MiyowaSAMember" xlink:label="loc_sncr_MiyowaSAMember_3F3057F58C23B47311DF2AC924A90118" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ABF4A9939D359E810E8F2AC924A90DAA" xlink:to="loc_sncr_MiyowaSAMember_3F3057F58C23B47311DF2AC924A90118" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyNumberOfPlaintiffs" xlink:label="loc_us-gaap_LossContingencyNumberOfPlaintiffs_C5E9E8AED53AB647A18B2AC924AAB2C3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_4FDB5625CD3E47DC2C2D2AC924AA05F1" xlink:to="loc_us-gaap_LossContingencyNumberOfPlaintiffs_C5E9E8AED53AB647A18B2AC924AAB2C3" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/Restructuring" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/RestructuringDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_098AB30E9C4B472B4FBE403DA6C501DA" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_FB8BA8E0368A09FC3D26403DA6C3D9A9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_098AB30E9C4B472B4FBE403DA6C501DA" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_FB8BA8E0368A09FC3D26403DA6C3D9A9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_B98928B3CA153B16DCB5403DA6C31A4D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_FB8BA8E0368A09FC3D26403DA6C3D9A9" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_B98928B3CA153B16DCB5403DA6C31A4D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_EA27CA2F92AA5CFC7A05403DA6C371E9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_B98928B3CA153B16DCB5403DA6C31A4D" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_EA27CA2F92AA5CFC7A05403DA6C371E9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_EA27CA2F92AA5CFC7A05403DA6C371E9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_B98928B3CA153B16DCB5403DA6C31A4D" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_EA27CA2F92AA5CFC7A05403DA6C371E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:label="loc_us-gaap_EmployeeSeveranceMember_ACEFA49B58F223E2066D403DA6C37EB1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_EA27CA2F92AA5CFC7A05403DA6C371E9" xlink:to="loc_us-gaap_EmployeeSeveranceMember_ACEFA49B58F223E2066D403DA6C37EB1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FacilityClosingMember" xlink:label="loc_us-gaap_FacilityClosingMember_8C590F53A8A5DF105F33403DA6C5B486" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_EA27CA2F92AA5CFC7A05403DA6C371E9" xlink:to="loc_us-gaap_FacilityClosingMember_8C590F53A8A5DF105F33403DA6C5B486" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_97D9699AB51EC8036DFD403DA6C57A62" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_FB8BA8E0368A09FC3D26403DA6C3D9A9" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_97D9699AB51EC8036DFD403DA6C57A62" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_3BF109580F29F826306F403DA6C55C88_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_97D9699AB51EC8036DFD403DA6C57A62" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_3BF109580F29F826306F403DA6C55C88_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_3BF109580F29F826306F403DA6C55C88" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_97D9699AB51EC8036DFD403DA6C57A62" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_3BF109580F29F826306F403DA6C55C88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccruedLiabilitiesMember" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_9B46F570E56A7AA5CF3A403DA6C5F296" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_3BF109580F29F826306F403DA6C55C88" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_9B46F570E56A7AA5CF3A403DA6C5F296" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringReserveRollForward" xlink:label="loc_us-gaap_RestructuringReserveRollForward_435A53AAD50FBE37B30A403DA6C5CDC9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_098AB30E9C4B472B4FBE403DA6C501DA" xlink:to="loc_us-gaap_RestructuringReserveRollForward_435A53AAD50FBE37B30A403DA6C5CDC9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringReserve" xlink:label="loc_us-gaap_RestructuringReserve_E6E0801049C654F11468403DA6C586F6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_435A53AAD50FBE37B30A403DA6C5CDC9" xlink:to="loc_us-gaap_RestructuringReserve_E6E0801049C654F11468403DA6C586F6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_930E91AAC39D7EA297C3403DA6C66BB4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_435A53AAD50FBE37B30A403DA6C5CDC9" xlink:to="loc_us-gaap_RestructuringCharges_930E91AAC39D7EA297C3403DA6C66BB4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsForRestructuring" xlink:label="loc_us-gaap_PaymentsForRestructuring_0FBC748B2C5E3E1933F6403DA6C6DD89" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_435A53AAD50FBE37B30A403DA6C5CDC9" xlink:to="loc_us-gaap_PaymentsForRestructuring_0FBC748B2C5E3E1933F6403DA6C6DD89" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/RestructuringTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/StockholdersEquity" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/StockholdersEquityBlackScholesAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED03F3FDF4341BD51407DDA7ABF8A630" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5A856C70C82069CBAC40DDA7ABF8B424" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED03F3FDF4341BD51407DDA7ABF8A630" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5A856C70C82069CBAC40DDA7ABF8B424" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_07F03BF3BB63BBE9706CDDA7ABF80B21" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5A856C70C82069CBAC40DDA7ABF8B424" xlink:to="loc_us-gaap_AwardTypeAxis_07F03BF3BB63BBE9706CDDA7ABF80B21" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AEC402D5C4C0F207C0ACDDA7ABF83270_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_07F03BF3BB63BBE9706CDDA7ABF80B21" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AEC402D5C4C0F207C0ACDDA7ABF83270_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AEC402D5C4C0F207C0ACDDA7ABF83270" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_07F03BF3BB63BBE9706CDDA7ABF80B21" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AEC402D5C4C0F207C0ACDDA7ABF83270" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_EmployeeAndDirectorsStockOptionsMember" xlink:label="loc_sncr_EmployeeAndDirectorsStockOptionsMember_752FC8A68370AAC5C1D4DDA7ABF8A317" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AEC402D5C4C0F207C0ACDDA7ABF83270" xlink:to="loc_sncr_EmployeeAndDirectorsStockOptionsMember_752FC8A68370AAC5C1D4DDA7ABF8A317" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_A6A4445CE2EF1B730F4ADDA7ABF8BAF1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ED03F3FDF4341BD51407DDA7ABF8A630" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_A6A4445CE2EF1B730F4ADDA7ABF8BAF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_EE049FD1FF340D400315DDA7ABF98B1D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_A6A4445CE2EF1B730F4ADDA7ABF8BAF1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_EE049FD1FF340D400315DDA7ABF98B1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_18231A6D310247D9AEA4DDA7ABF9ADC7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_A6A4445CE2EF1B730F4ADDA7ABF8BAF1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_18231A6D310247D9AEA4DDA7ABF9ADC7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_424A33AA1FADBE1BC5DBDDA7ABF96F85" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_A6A4445CE2EF1B730F4ADDA7ABF8BAF1" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_424A33AA1FADBE1BC5DBDDA7ABF96F85" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_0C32C2DEE363AAB59F37DDA7ABF9C0C9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_A6A4445CE2EF1B730F4ADDA7ABF8BAF1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_0C32C2DEE363AAB59F37DDA7ABF9C0C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_A6722AF2D8BD6C958757DDA7ABF964AD" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_A6A4445CE2EF1B730F4ADDA7ABF8BAF1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_A6722AF2D8BD6C958757DDA7ABF964AD" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/StockholdersEquityEsppAndOtherDisclosuresDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_60D17D811C300D3F230C44A12B21F561" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8B7624B72CC93C868E3144A12B20C1CB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_60D17D811C300D3F230C44A12B21F561" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8B7624B72CC93C868E3144A12B20C1CB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_313CD72097AAC05BC63444A12B205953" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8B7624B72CC93C868E3144A12B20C1CB" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_313CD72097AAC05BC63444A12B205953" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_F8EC5228F387BE4F086044A12B210419_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_313CD72097AAC05BC63444A12B205953" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_F8EC5228F387BE4F086044A12B210419_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_F8EC5228F387BE4F086044A12B210419" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_313CD72097AAC05BC63444A12B205953" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_F8EC5228F387BE4F086044A12B210419" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeStockMember" xlink:label="loc_us-gaap_EmployeeStockMember_9E3D272FB65C8A2EBE6044A12B219B8A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_F8EC5228F387BE4F086044A12B210419" xlink:to="loc_us-gaap_EmployeeStockMember_9E3D272FB65C8A2EBE6044A12B219B8A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_A985B68D2A46E9A1F2AE44A12B210FA4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_60D17D811C300D3F230C44A12B21F561" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_A985B68D2A46E9A1F2AE44A12B210FA4" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_TermOfEmployeeStockPurchasePlan" xlink:label="loc_sncr_TermOfEmployeeStockPurchasePlan_0697C306BABE142E508E44A12B21DC2B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_A985B68D2A46E9A1F2AE44A12B210FA4" xlink:to="loc_sncr_TermOfEmployeeStockPurchasePlan_0697C306BABE142E508E44A12B21DC2B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_4097D04FDD3385CB11A444A12B2164AF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_A985B68D2A46E9A1F2AE44A12B210FA4" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_4097D04FDD3385CB11A444A12B2164AF" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_EmployeeStockPurchasePlanPayrollWithholdingPeriod" xlink:label="loc_sncr_EmployeeStockPurchasePlanPayrollWithholdingPeriod_8139D1D0B0C0F37E73F344A12B21CC04" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_A985B68D2A46E9A1F2AE44A12B210FA4" xlink:to="loc_sncr_EmployeeStockPurchasePlanPayrollWithholdingPeriod_8139D1D0B0C0F37E73F344A12B21CC04" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_68E4C97E201910DAD59844A12B2130B1" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_A985B68D2A46E9A1F2AE44A12B210FA4" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_68E4C97E201910DAD59844A12B2130B1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_BE126B0C8A5CBD7BBE6744A12B218A63" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_A985B68D2A46E9A1F2AE44A12B210FA4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_BE126B0C8A5CBD7BBE6744A12B218A63" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_CommonStockMaximumNumberofSharesAuthorizedWithinanyPurchasePeriod" xlink:label="loc_sncr_CommonStockMaximumNumberofSharesAuthorizedWithinanyPurchasePeriod_1638B30BC5ECECCE713D44A12B210D8A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_A985B68D2A46E9A1F2AE44A12B210FA4" xlink:to="loc_sncr_CommonStockMaximumNumberofSharesAuthorizedWithinanyPurchasePeriod_1638B30BC5ECECCE713D44A12B210D8A" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_CommonStockMaximumValueofSharesAuthorizedWithinanyCalendarYear" xlink:label="loc_sncr_CommonStockMaximumValueofSharesAuthorizedWithinanyCalendarYear_B0FCD257D4138E4F838844A12B21E427" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_A985B68D2A46E9A1F2AE44A12B210FA4" xlink:to="loc_sncr_CommonStockMaximumValueofSharesAuthorizedWithinanyCalendarYear_B0FCD257D4138E4F838844A12B21E427" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/StockholdersEquityRestrictedStockDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_80F467E970D20FEEE2F8772FE8509763" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F9872C0FCD16F5B24E00772FE8505524" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_80F467E970D20FEEE2F8772FE8509763" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F9872C0FCD16F5B24E00772FE8505524" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_54B9DBFEB979C9F1C3E8772FE8504CF0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F9872C0FCD16F5B24E00772FE8505524" xlink:to="loc_us-gaap_AwardTypeAxis_54B9DBFEB979C9F1C3E8772FE8504CF0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CB6A528C9EB886C5468F772FE850D625_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_54B9DBFEB979C9F1C3E8772FE8504CF0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CB6A528C9EB886C5468F772FE850D625_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CB6A528C9EB886C5468F772FE850D625" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_54B9DBFEB979C9F1C3E8772FE8504CF0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CB6A528C9EB886C5468F772FE850D625" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_88A2A185EB9780334031772FE850E2A4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CB6A528C9EB886C5468F772FE850D625" xlink:to="loc_us-gaap_RestrictedStockMember_88A2A185EB9780334031772FE850E2A4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_A7078F3BAB04421F8BA1772FE851F6B5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_80F467E970D20FEEE2F8772FE8509763" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_A7078F3BAB04421F8BA1772FE851F6B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_208E39774AC2DDD0FF5B772FE851A953" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_A7078F3BAB04421F8BA1772FE851F6B5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_208E39774AC2DDD0FF5B772FE851A953" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_CD2550292782B3FC9B9D772FE851761F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_A7078F3BAB04421F8BA1772FE851F6B5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_CD2550292782B3FC9B9D772FE851761F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_A473AB765C624E41ADE4772FE851000C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_A7078F3BAB04421F8BA1772FE851F6B5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_A473AB765C624E41ADE4772FE851000C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_5AE65D6C3A4E7CA91967772FE85122CE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_A7078F3BAB04421F8BA1772FE851F6B5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_5AE65D6C3A4E7CA91967772FE85122CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_DF3EEC0F5A7F6BD2747E772FE85192DC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_80F467E970D20FEEE2F8772FE8509763" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_DF3EEC0F5A7F6BD2747E772FE85192DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_EC6BF5348B7857248226772FE851668A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_DF3EEC0F5A7F6BD2747E772FE85192DC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_EC6BF5348B7857248226772FE851668A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8D7FA9223961FA6857B1772FE85104A4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_DF3EEC0F5A7F6BD2747E772FE85192DC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8D7FA9223961FA6857B1772FE85104A4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_F099B75E347E0EBB065C772FE851F63B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_DF3EEC0F5A7F6BD2747E772FE85192DC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_F099B75E347E0EBB065C772FE851F63B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_A2F9EC76085DB290C7C7772FE85117C3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_DF3EEC0F5A7F6BD2747E772FE85192DC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_A2F9EC76085DB290C7C7772FE85117C3" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/StockholdersEquityStockBasedCompensationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B6943616273B676482FDDDA7ABDCB454" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4117ACFE9D77A9755250DDA7ABDBF3E0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B6943616273B676482FDDDA7ABDCB454" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4117ACFE9D77A9755250DDA7ABDBF3E0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_E6A0016464BE72945AB6DDA7ABDB72EA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4117ACFE9D77A9755250DDA7ABDBF3E0" xlink:to="loc_us-gaap_AwardTypeAxis_E6A0016464BE72945AB6DDA7ABDB72EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76ACE09B4679CD3671EDDDA7ABDBFD9E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_E6A0016464BE72945AB6DDA7ABDB72EA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76ACE09B4679CD3671EDDDA7ABDBFD9E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76ACE09B4679CD3671EDDDA7ABDBFD9E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_E6A0016464BE72945AB6DDA7ABDB72EA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76ACE09B4679CD3671EDDDA7ABDBFD9E" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_EmployeeAndDirectorsStockOptionsMember" xlink:label="loc_sncr_EmployeeAndDirectorsStockOptionsMember_F2BAD6F34CD01A3E46D0DDA7ABDBCBFC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76ACE09B4679CD3671EDDDA7ABDBFD9E" xlink:to="loc_sncr_EmployeeAndDirectorsStockOptionsMember_F2BAD6F34CD01A3E46D0DDA7ABDBCBFC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_B873B579AD2EF5EF3AFDDDA7ABDC9D33" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_76ACE09B4679CD3671EDDDA7ABDBFD9E" xlink:to="loc_us-gaap_RestrictedStockMember_B873B579AD2EF5EF3AFDDDA7ABDC9D33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_94EE9DCE89B4DA22024ADDA7ABDCCCF0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4117ACFE9D77A9755250DDA7ABDBF3E0" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_94EE9DCE89B4DA22024ADDA7ABDCCCF0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_EF92BD577973C2417BFADDA7ABDC4111_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_94EE9DCE89B4DA22024ADDA7ABDCCCF0" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_EF92BD577973C2417BFADDA7ABDC4111_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_EF92BD577973C2417BFADDA7ABDC4111" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_94EE9DCE89B4DA22024ADDA7ABDCCCF0" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_EF92BD577973C2417BFADDA7ABDC4111" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeStockMember" xlink:label="loc_us-gaap_EmployeeStockMember_C62B6926D492565B59BEDDA7ABDC5FCD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_EF92BD577973C2417BFADDA7ABDC4111" xlink:to="loc_us-gaap_EmployeeStockMember_C62B6926D492565B59BEDDA7ABDC5FCD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAggregateDisclosuresAbstract" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAggregateDisclosuresAbstract_8F32AE4250A6A998B1BEDDA7ABDC5A00" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B6943616273B676482FDDDA7ABDCB454" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationAggregateDisclosuresAbstract_8F32AE4250A6A998B1BEDDA7ABDC5A00" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_55F59E44A3610D1B0FB0DDA7ABDCE636" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAggregateDisclosuresAbstract_8F32AE4250A6A998B1BEDDA7ABDC5A00" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_55F59E44A3610D1B0FB0DDA7ABDCE636" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_523FFFD58B86D2466980DDA7ABDC0B58" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAggregateDisclosuresAbstract_8F32AE4250A6A998B1BEDDA7ABDC5A00" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_523FFFD58B86D2466980DDA7ABDC0B58" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_0E330F0A1C1F48E24BC6DDA7ABDC3978" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAggregateDisclosuresAbstract_8F32AE4250A6A998B1BEDDA7ABDC5A00" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_0E330F0A1C1F48E24BC6DDA7ABDC3978" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_2FD4E54C918E97023A08DDA7ABE1E42F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAggregateDisclosuresAbstract_8F32AE4250A6A998B1BEDDA7ABDC5A00" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_2FD4E54C918E97023A08DDA7ABE1E42F" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/StockholdersEquityStockOptionsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/StockholdersEquityTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_872A28D7011115D9D58C772FE863CE0D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_1789A6E95144F722199F772FE8638206" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_872A28D7011115D9D58C772FE863CE0D" xlink:to="loc_us-gaap_StatementTable_1789A6E95144F722199F772FE8638206" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_AD973640D540AA736DA4772FE86344C4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1789A6E95144F722199F772FE8638206" xlink:to="loc_us-gaap_AwardTypeAxis_AD973640D540AA736DA4772FE86344C4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CF2A84499656AC9B10E0772FE863F782_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_AD973640D540AA736DA4772FE86344C4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CF2A84499656AC9B10E0772FE863F782_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CF2A84499656AC9B10E0772FE863F782" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_AD973640D540AA736DA4772FE86344C4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CF2A84499656AC9B10E0772FE863F782" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_EmployeeAndDirectorsStockOptionsMember" xlink:label="loc_sncr_EmployeeAndDirectorsStockOptionsMember_646C59414CEEB8F1FE1D772FE8632817" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CF2A84499656AC9B10E0772FE863F782" xlink:to="loc_sncr_EmployeeAndDirectorsStockOptionsMember_646C59414CEEB8F1FE1D772FE8632817" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_1194C3BC93745570BA71772FE8633DC4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CF2A84499656AC9B10E0772FE863F782" xlink:to="loc_us-gaap_RestrictedStockMember_1194C3BC93745570BA71772FE8633DC4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock_4170F22AF17753B7AAA2772FE863E1CC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_872A28D7011115D9D58C772FE863CE0D" xlink:to="loc_us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock_4170F22AF17753B7AAA2772FE863E1CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_4F9414B846B8E0295024772FE86322FD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_872A28D7011115D9D58C772FE863CE0D" xlink:to="loc_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_4F9414B846B8E0295024772FE86322FD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_F01CEC4DAD22E4EB95D5772FE8631B26" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_872A28D7011115D9D58C772FE863CE0D" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_F01CEC4DAD22E4EB95D5772FE8631B26" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValueTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValueTableTextBlock_C2B4C09E3F45F597CCA5772FE8631F35" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_872A28D7011115D9D58C772FE863CE0D" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValueTableTextBlock_C2B4C09E3F45F597CCA5772FE8631F35" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_6892815E1B85CED5E578772FE86398EA" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_872A28D7011115D9D58C772FE863CE0D" xlink:to="loc_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_6892815E1B85CED5E578772FE86398EA" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/StockholdersEquityTreasuryStockDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityClassOfTreasuryStockLineItems" xlink:label="loc_us-gaap_EquityClassOfTreasuryStockLineItems_C795E79F18E7D79AD80B71409E3E9AAF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ClassOfTreasuryStockTable" xlink:label="loc_us-gaap_ClassOfTreasuryStockTable_13B3473592D36633DEDB71409E3E48D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_C795E79F18E7D79AD80B71409E3E9AAF" xlink:to="loc_us-gaap_ClassOfTreasuryStockTable_13B3473592D36633DEDB71409E3E48D0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareRepurchaseProgramAxis" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_B6EF52C3F7CB02BB7E5771409E3E9E20" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_13B3473592D36633DEDB71409E3E48D0" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_B6EF52C3F7CB02BB7E5771409E3E9E20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_C555D371C717D4E2758271409E3E21F8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_B6EF52C3F7CB02BB7E5771409E3E9E20" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_C555D371C717D4E2758271409E3E21F8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_C555D371C717D4E2758271409E3E21F8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_B6EF52C3F7CB02BB7E5771409E3E9E20" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_C555D371C717D4E2758271409E3E21F8" xlink:type="arc" />
    <link:loc xlink:href="sncr-20160930.xsd#sncr_ShareRepurchaseProgram2016Member" xlink:label="loc_sncr_ShareRepurchaseProgram2016Member_7983160266E32266EFBB71409E3E7820" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_C555D371C717D4E2758271409E3E21F8" xlink:to="loc_sncr_ShareRepurchaseProgram2016Member_7983160266E32266EFBB71409E3E7820" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract" xlink:label="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_9EA5D5B2C5A8106A453371409E3EF37E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_C795E79F18E7D79AD80B71409E3E9AAF" xlink:to="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_9EA5D5B2C5A8106A453371409E3EF37E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_6E54F90AF6E542DE8A3B71409E3E4CAE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_9EA5D5B2C5A8106A453371409E3EF37E" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_6E54F90AF6E542DE8A3B71409E3E4CAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_43D279A6441BE34FF83F71409E3E4500" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_9EA5D5B2C5A8106A453371409E3EF37E" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_43D279A6441BE34FF83F71409E3E4500" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_602138DDB3A32A29088B71409E3E9622" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_9EA5D5B2C5A8106A453371409E3EF37E" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_602138DDB3A32A29088B71409E3E9622" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.synchronoss.com/role/SubsequentEventsReview" xlink:type="extended" />
</link:linkbase>