late 14c., envolupen, "be involved in," from Old French envoleper (10c., Modern French envelopper) "envelop, cover; fold up," from en- "in" (see en- (1)) + voloper "wrap up," of uncertain origin, perhaps Celtic (see Gamillscheg, Diez). Literal sense is from 1580s. Related: Enveloped; enveloping.