late 14c., eschaunge, "act of reciprocal giving and receiving," from Anglo-French eschaunge, Old French eschange (Modern French échange), from Late Latin excambium, from excambiare, from Latin ex "out" (see ex-) + cambire "barter" (see change (v.)). The practice of merchants or lenders meeting at certain places to exchange bills of debt led to the meaning "building for mercantile business" (1580s).
late 15c. (Caxton), in commerce, "to part with in return for some equivalent, transfer for a recompense, barter," from Old French eschangier "exchange, barter" (Modern French échanger), from Vulgar Latin *excambiare (source of Italian scambiare); see exchange (n.). Non-commercial sense of "to give and receive reciprocally" is from c. 1600. Related: Exchanged; exchanging.