engage from Late Middle English:
Gage is an old word that means ‘a valued object deposited as a guarantee of good faith’ and, as a verb, ‘to give as a pledge’. An Old French word related to wage (Middle English) and wedding ( see marry), it is the root of engage. Engage originally meant ‘give as a pledge’ and ‘pawn or mortgage’, later coming to express the ideas ‘to pledge or guarantee’ and ‘to enter into a contract’. People have been getting engaged to be married since the beginning of the 18th century: the first recorded example is by Henry Fielding (1707–54), author of Joseph Andrews and Tom Jones.