1620s, "feigned," past participle adjective from simulate (v.). Meaning "imitative for purposes of experiment or training" is from 1966 (agent noun simulator in the related sense dates from 1947; cf. simulation). In commercial jargon, "artificial, imitation" by 1942.
1620s, "feign, pretend, assume falsely" (implied in simulated), back-formation from simulation or else from Latin simulatus, past participle of simulare "to make like, imitate, copy." Meaning "to use a model to imitate certain conditions for purposes of study or training" is from 1947. Related: Simulating.