early 15c., from Latin assimilatus "feigned, pretended, fictitious," past participle of assimilare "to make like," from ad- "to" (see ad-) + simulare "make similar," from similis "like, resembling" (see similar). Originally transitive (with to); intransitive use first recorded 1837. Related: Assimilated; assimilating.[assimilate etymology, assimilate origin, 英语词源]