earlly 14c., transitive and intransitive, from Old French assembler "come together, join, unite; gather" (11c.), from Latin assimulare "to make like, liken, compare; copy, imitate; feign, pretend," later "to gather together," from ad- "to" (see ad-) + simulare "to make like" (see simulation). In Middle English and in Old French it also was a euphemism for "to couple sexually." Meaning "to put parts together" in manufacturing is from 1852. Related: Assembled; assembling. Assemble together is redundant.