swap (v.)

c. 1200, "to strike, strike the hands together," of uncertain origin, possibly imitative of the sound of hitting or slapping. The sense of "to exchange, barter, trade" is first recorded 1590s, possibly from the notion of slapping hands together as a sign of agreement in bargaining (as in strike a bargain). Related: Swapped; swapping. The noun in this sense is attested from 1620s; earlier "a striking, an act of striking" (mid-13c.). Swap-meet attested from 1968, American English.

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Definitions of swap from WordNet
swap (v.)
exchange or give (something) in exchange for;
Synonyms: trade / swop / switch
swap (v.)
move (a piece of a program) into memory, in computer science;
swap (n.)
an equal exchange;
Synonyms: barter / swop / trade