noun
A provision in a contract or in a testamentary or other legal document that,
upon the occurrence of specific events, a partyÂ’s future interest in certain
property will prematurely vest. For example, in many loan or mortgage
agreements, provision is made that if some specified event occurs, such as the
debtorÂ’s failure to pay an installment, the creditor may declare the entire
outstanding balance to be immediately due.