<?xml version="1.0" encoding="US-ASCII" standalone="no"?>
    <!-- Field: Doc-Info; Name: Generator; Value: GoFiler Complete; Version: 6.5a -->
    <!-- Field: Doc-Info; Name: VendorURI; Value: https://www.novaworks.com -->
    <!-- Field: Doc-Info; Name: Status; Value: 0x00000000 -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#Cover" roleURI="http://mysizeid.com/role/Cover" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#InterimBalanceSheets" roleURI="http://mysizeid.com/role/InterimBalanceSheets" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#InterimBalanceSheetsParenthetical" roleURI="http://mysizeid.com/role/InterimBalanceSheetsParenthetical" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#InterimStatementsOfComprehensiveLoss" roleURI="http://mysizeid.com/role/InterimStatementsOfComprehensiveLoss" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#InterimStatementsOfChangesInStockholdersEquity" roleURI="http://mysizeid.com/role/InterimStatementsOfChangesInStockholdersEquity" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#InterimStatementsOfChangesInStockholdersEquityParenthetical" roleURI="http://mysizeid.com/role/InterimStatementsOfChangesInStockholdersEquityParenthetical" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#InterimStatementsOfCashFlows" roleURI="http://mysizeid.com/role/InterimStatementsOfCashFlows" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#General" roleURI="http://mysizeid.com/role/General" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#SignificantAccountingPolicies" roleURI="http://mysizeid.com/role/SignificantAccountingPolicies" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#FinancialInstruments" roleURI="http://mysizeid.com/role/FinancialInstruments" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#StockBasedCompensation" roleURI="http://mysizeid.com/role/StockBasedCompensation" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#ContingenciesAndCommitments" roleURI="http://mysizeid.com/role/ContingenciesAndCommitments" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#OperatingSegments" roleURI="http://mysizeid.com/role/OperatingSegments" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#SignificantEventsDuringReportingPeriod" roleURI="http://mysizeid.com/role/SignificantEventsDuringReportingPeriod" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#SubsequentEventsAfterReportingPeriod" roleURI="http://mysizeid.com/role/SubsequentEventsAfterReportingPeriod" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#SignificantAccountingPoliciesPolicies" roleURI="http://mysizeid.com/role/SignificantAccountingPoliciesPolicies" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#FinancialInstrumentsTables" roleURI="http://mysizeid.com/role/FinancialInstrumentsTables" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#StockBasedCompensationTables" roleURI="http://mysizeid.com/role/StockBasedCompensationTables" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#OperatingSegmentsTables" roleURI="http://mysizeid.com/role/OperatingSegmentsTables" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#GeneralDetailsNarrative" roleURI="http://mysizeid.com/role/GeneralDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#ScheduleOfSignificantAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails" roleURI="http://mysizeid.com/role/ScheduleOfSignificantAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#ScheduleOfSignificantAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetailsParenthetical" roleURI="http://mysizeid.com/role/ScheduleOfSignificantAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetailsParenthetical" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#ScheduleOfStockBasedCompensationExpensesDetails" roleURI="http://mysizeid.com/role/ScheduleOfStockBasedCompensationExpensesDetails" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#StockBasedCompensationDetailsNarrative" roleURI="http://mysizeid.com/role/StockBasedCompensationDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#ContingenciesAndCommitmentsDetailsNarrative" roleURI="http://mysizeid.com/role/ContingenciesAndCommitmentsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#ScheduleOfReportableOperatingSegmentsDetails" roleURI="http://mysizeid.com/role/ScheduleOfReportableOperatingSegmentsDetails" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#OperatingSegmentsDetailsNarrative" roleURI="http://mysizeid.com/role/OperatingSegmentsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#SignificantEventsDuringReportingPeriodDetailsNarrative" roleURI="http://mysizeid.com/role/SignificantEventsDuringReportingPeriodDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="mysz-20260630.xsd#SubsequentEventsAfterReportingPeriodDetailsNarrative" roleURI="http://mysizeid.com/role/SubsequentEventsAfterReportingPeriodDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#PvpExecutiveCategoriesOnly" roleURI="http://xbrl.sec.gov/ecd/role/PvpExecutiveCategoriesOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#PvpAdjustmentsOnly" roleURI="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#IndividualsOnly" roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#AwardTypeOnly" roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#TradingArrangmentsOnly" roleURI="http://xbrl.sec.gov/ecd/role/TradingArrangementsOnly" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll" arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/Cover" xlink:title="00000001 - Document - Cover" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/InterimBalanceSheets" xlink:title="00000002 - Statement - Condensed Consolidated Interim Balance Sheets (Unaudited)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/InterimBalanceSheetsParenthetical" xlink:title="00000003 - Statement - Condensed Consolidated Interim Balance Sheets (Unaudited) (Parenthetical)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/InterimStatementsOfComprehensiveLoss" xlink:title="00000004 - Statement - Condensed Consolidated Interim Statements of Comprehensive Loss (Unaudited)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/InterimStatementsOfChangesInStockholdersEquity" xlink:title="00000005 - Statement - Condensed Consolidated Interim Statements of Changes in Stockholders&apos; Equity (Unaudited)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaapAdditionalPaidInCapitalMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapAdditionalPaidInCapitalMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapAccumulatedOtherComprehensiveIncomeMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaapRetainedEarningsMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapRetainedEarningsMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaapStockholdersEquity_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockholdersEquity_60" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaapSharesOutstanding_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharesOutstanding_60" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueShareBasedCompensation_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueShareBasedCompensation_60" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesShareBasedCompensation_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesShareBasedCompensation_60" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueOther_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueOther_60" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesOther_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesOther_60" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="loc_us-gaapComprehensiveIncomeNetOfTax_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapComprehensiveIncomeNetOfTax_60" xlink:type="arc" order="7" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/InterimStatementsOfChangesInStockholdersEquityParenthetical" xlink:title="00000006 - Statement - Condensed Consolidated Interim Statements of Changes in Stockholders&apos; Equity (Unaudited) (Parenthetical)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/InterimStatementsOfCashFlows" xlink:title="00000007 - Statement - Condensed Consolidated Interim Statements of Cash Flows (Unaudited)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/General" xlink:title="999013 - Disclosure - General" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/SignificantAccountingPolicies" xlink:title="999014 - Disclosure - Significant Accounting Policies" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/FinancialInstruments" xlink:title="999015 - Disclosure - Financial Instruments" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/StockBasedCompensation" xlink:title="999016 - Disclosure - Stock Based Compensation" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/ContingenciesAndCommitments" xlink:title="999017 - Disclosure - Contingencies and Commitments" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/OperatingSegments" xlink:title="999018 - Disclosure - Operating Segments" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/SignificantEventsDuringReportingPeriod" xlink:title="999019 - Disclosure - Significant events during the reporting period" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/SubsequentEventsAfterReportingPeriod" xlink:title="999020 - Disclosure - Subsequent events after the reporting period" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/SignificantAccountingPoliciesPolicies" xlink:title="999021 - Disclosure - Significant Accounting Policies (Policies)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/FinancialInstrumentsTables" xlink:title="999022 - Disclosure - Financial Instruments (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/StockBasedCompensationTables" xlink:title="999023 - Disclosure - Stock Based Compensation (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/OperatingSegmentsTables" xlink:title="999024 - Disclosure - Operating Segments (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/GeneralDetailsNarrative" xlink:title="999025 - Disclosure - General (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:label="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:label="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_ShareSaleAndPurchaseAgreementMember" xlink:label="loc_MYSZShareSaleAndPurchaseAgreementMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_MYSZShareSaleAndPurchaseAgreementMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_40" xlink:type="arc" order="43" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Cash" xlink:label="loc_us-gaapCash_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapCash_100" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_PercentageOfShareCapital" xlink:label="loc_MYSZPercentageOfShareCapital_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_MYSZPercentageOfShareCapital_100" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForLegalSettlements" xlink:label="loc_us-gaapPaymentsForLegalSettlements_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapPaymentsForLegalSettlements_100" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_100" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_FairValueOfPurchasePriceAllocation" xlink:label="loc_MYSZFairValueOfPurchasePriceAllocation_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_MYSZFairValueOfPurchasePriceAllocation_100" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightOutstanding" xlink:label="loc_us-gaapClassOfWarrantOrRightOutstanding_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightOutstanding_100" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaapRetainedEarningsAccumulatedDeficit_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapRetainedEarningsAccumulatedDeficit_100" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_NasdaqStockMarketDescription" xlink:label="loc_MYSZNasdaqStockMarketDescription_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_MYSZNasdaqStockMarketDescription_100" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaapProceedsFromIssuanceOfCommonStock_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOfCommonStock_100" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_CommissionPercentage" xlink:label="loc_MYSZCommissionPercentage_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_MYSZCommissionPercentage_100" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" xlink:label="loc_us-gaapSaleOfStockNumberOfSharesIssuedInTransaction_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapSaleOfStockNumberOfSharesIssuedInTransaction_100" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction" xlink:label="loc_us-gaapSaleOfStockConsiderationReceivedOnTransaction_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapSaleOfStockConsiderationReceivedOnTransaction_100" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityReverseStockSplit" xlink:label="loc_us-gaapStockholdersEquityReverseStockSplit_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapStockholdersEquityReverseStockSplit_100" xlink:type="arc" order="12" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/ScheduleOfSignificantAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails" xlink:title="999026 - Disclosure - Schedule of Significant Assets and Liabilities Measured at Fair Value on Recurring Basis (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueOffBalanceSheetRisksDisclosureInformationLineItems" xlink:label="loc_us-gaapFairValueOffBalanceSheetRisksDisclosureInformationLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfFairValueOffBalanceSheetRisksTable" xlink:label="loc_us-gaapScheduleOfFairValueOffBalanceSheetRisksTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFairValueOffBalanceSheetRisksDisclosureInformationLineItems" xlink:to="loc_us-gaapScheduleOfFairValueOffBalanceSheetRisksTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfFairValueOffBalanceSheetRisksTable" xlink:to="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaapFairValueInputsLevel1Member_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel1Member_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaapFairValueInputsLevel2Member_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel2Member_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaapFairValueInputsLevel3Member_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel3Member_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsFairValueDisclosure" xlink:label="loc_us-gaapInvestmentsFairValueDisclosure_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueOffBalanceSheetRisksDisclosureInformationLineItems" xlink:to="loc_us-gaapInvestmentsFairValueDisclosure_70" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/ScheduleOfSignificantAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetailsParenthetical" xlink:title="999027 - Disclosure - Schedule of Significant Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) (Parenthetical)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/ScheduleOfStockBasedCompensationExpensesDetails" xlink:title="999028 - Disclosure - Schedule of Stock Based Compensation Expenses (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaapAwardTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaapAwardTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_ResearchAndDevelopmentMember" xlink:label="loc_MYSZResearchAndDevelopmentMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_MYSZResearchAndDevelopmentMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_SalesAndMarketingMember" xlink:label="loc_MYSZSalesAndMarketingMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_MYSZSalesAndMarketingMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_GeneralAndAdministrativeMember" xlink:label="loc_MYSZGeneralAndAdministrativeMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_MYSZGeneralAndAdministrativeMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeBenefitsAndShareBasedCompensation" xlink:label="loc_us-gaapEmployeeBenefitsAndShareBasedCompensation_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapEmployeeBenefitsAndShareBasedCompensation_170" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/StockBasedCompensationDetailsNarrative" xlink:title="999029 - Disclosure - Stock Based Compensation (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaapPlanNameAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaapPlanNameAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_TwoThousandSeventeenEmployeePlanMember" xlink:label="loc_MYSZTwoThousandSeventeenEmployeePlanMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_MYSZTwoThousandSeventeenEmployeePlanMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_60" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_60" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaapAllocatedShareBasedCompensationExpense_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapAllocatedShareBasedCompensationExpense_60" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/ContingenciesAndCommitmentsDetailsNarrative" xlink:title="999030 - Disclosure - Contingencies and Commitments (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaapLossContingenciesTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLossContingenciesTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLossContingenciesTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_ShimonShukronMember" xlink:label="loc_MYSZShimonShukronMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_MYSZShimonShukronMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyDamagesSoughtValue" xlink:label="loc_us-gaapLossContingencyDamagesSoughtValue_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapLossContingencyDamagesSoughtValue_30" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/ScheduleOfReportableOperatingSegmentsDetails" xlink:title="999031 - Disclosure - Schedule of Reportable Operating Segments (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaapSegmentReportingInformationLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srtConsolidationItemsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="loc_srtConsolidationItemsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srtConsolidationItemsDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtConsolidationItemsAxis" xlink:to="loc_srtConsolidationItemsDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srtConsolidationItemsDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtConsolidationItemsAxis" xlink:to="loc_srtConsolidationItemsDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaapOperatingSegmentsMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtConsolidationItemsDomain" xlink:to="loc_us-gaapOperatingSegmentsMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaapStatementBusinessSegmentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="loc_us-gaapStatementBusinessSegmentsAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaapSegmentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementBusinessSegmentsAxis" xlink:to="loc_us-gaapSegmentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaapSegmentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementBusinessSegmentsAxis" xlink:to="loc_us-gaapSegmentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_FashionECommercePlatformMember" xlink:label="loc_MYSZFashionECommercePlatformMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentDomain" xlink:to="loc_MYSZFashionECommercePlatformMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_SaasSolutionsMember" xlink:label="loc_MYSZSaasSolutionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentDomain" xlink:to="loc_MYSZSaasSolutionsMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_ResalePlatformMember" xlink:label="loc_MYSZResalePlatformMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentDomain" xlink:to="loc_MYSZResalePlatformMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_OthersMember" xlink:label="loc_MYSZOthersMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentDomain" xlink:to="loc_MYSZOthersMember_30" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_290" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfRevenue" xlink:label="loc_us-gaapCostOfRevenue_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapCostOfRevenue_290" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaapResearchAndDevelopmentExpense_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapResearchAndDevelopmentExpense_290" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_AmazonFees" xlink:label="loc_MYSZAmazonFees_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_MYSZAmazonFees_290" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SellingAndMarketingExpense" xlink:label="loc_us-gaapSellingAndMarketingExpense_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapSellingAndMarketingExpense_290" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherExpenses" xlink:label="loc_us-gaapOtherExpenses_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapOtherExpenses_290" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaapOperatingIncomeLoss_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapOperatingIncomeLoss_290" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaapNonoperatingIncomeExpense_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapNonoperatingIncomeExpense_290" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="loc_us-gaapIncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapIncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_290" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaapAmortizationOfIntangibleAssets_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapAmortizationOfIntangibleAssets_290" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaapShareBasedCompensation_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapShareBasedCompensation_290" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets" xlink:label="loc_us-gaapAssets_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapAssets_290" xlink:type="arc" order="11" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/OperatingSegmentsDetailsNarrative" xlink:title="999032 - Disclosure - Operating Segments (Details Narrative)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/SignificantEventsDuringReportingPeriodDetailsNarrative" xlink:title="999033 - Disclosure - Significant events during the reporting period (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:label="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:label="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_MarketOfferingAgreementMember" xlink:label="loc_MYSZMarketOfferingAgreementMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_MYSZMarketOfferingAgreementMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_CapitalAdvanceAgreementMember" xlink:label="loc_MYSZCapitalAdvanceAgreementMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_MYSZCapitalAdvanceAgreementMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:label="loc_us-gaapProceedsFromIssuanceOrSaleOfEquity_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOrSaleOfEquity_50" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesOther_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesOther_50" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueOther_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueOther_50" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_UpfrontCashAdvance" xlink:label="loc_MYSZUpfrontCashAdvance_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_MYSZUpfrontCashAdvance_50" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractualObligation" xlink:label="loc_us-gaapContractualObligation_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapContractualObligation_50" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_CapitalFee" xlink:label="loc_MYSZCapitalFee_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_MYSZCapitalFee_50" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayable" xlink:label="loc_us-gaapLoansPayable_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapLoansPayable_50" xlink:type="arc" order="6" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://mysizeid.com/role/SubsequentEventsAfterReportingPeriodDetailsNarrative" xlink:title="999034 - Disclosure - Subsequent events after the reporting period (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaapSubsequentEventLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaapSubsequentEventTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapSubsequentEventTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_EquityPurchaseAgreementMember" xlink:label="loc_MYSZEquityPurchaseAgreementMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_MYSZEquityPurchaseAgreementMember_20" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_CombinationOfSharesDescription" xlink:label="loc_MYSZCombinationOfSharesDescription_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_MYSZCombinationOfSharesDescription_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityReverseStockSplit" xlink:label="loc_us-gaapStockholdersEquityReverseStockSplit_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapStockholdersEquityReverseStockSplit_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" xlink:label="loc_us-gaapSaleOfStockNumberOfSharesIssuedInTransaction_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapSaleOfStockNumberOfSharesIssuedInTransaction_40" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:label="loc_us-gaapProceedsFromIssuanceOrSaleOfEquity_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOrSaleOfEquity_40" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction" xlink:label="loc_us-gaapSaleOfStockConsiderationReceivedOnTransaction_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapSaleOfStockConsiderationReceivedOnTransaction_40" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_40" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityCommitmentFeeDescription" xlink:label="loc_us-gaapLineOfCreditFacilityCommitmentFeeDescription_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapLineOfCreditFacilityCommitmentFeeDescription_40" xlink:type="arc" order="6" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/role/PvpExecutiveCategoriesOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_ResearchAndDevelopmentMember" xlink:label="loc_MYSZResearchAndDevelopmentMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_MYSZResearchAndDevelopmentMember" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_SalesAndMarketingMember" xlink:label="loc_MYSZSalesAndMarketingMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_MYSZSalesAndMarketingMember" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="mysz-20260630.xsd#MYSZ_GeneralAndAdministrativeMember" xlink:label="loc_MYSZGeneralAndAdministrativeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_MYSZGeneralAndAdministrativeMember" xlink:type="arc" order="20" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/role/TradingArrangementsOnly" />
</link:linkbase>
