1250-1300; (v.) Middle Englisheschaungen < Anglo-Frencheschaungier < Vulgar Latin*excambiāre (see ex-, change); (noun) Middle Englisheschaunge < Anglo-French (Old Frencheschange), derivative of eschaungier; modern spelling with ex- on the model of ex-1
preexchange, verb (used with object), preexchanged, preexchanging.
late 14c., from Anglo-Fr. eschaunge, from O.Fr. eschangier, from V.L. *excambiare, from L. ex- "out" + cambire "barter" (see change). Sense of merchants or lenders meeting to exchange bills of debt led to meaning "building for mercantile business" (1580s). Related: Exchanged; exchanging.