c.1400, "emulation; act of copying," from Old French imitacion, from Latin imitationem (nominative imitatio) "a copying, imitation," from past participle stem of imitari "to copy, portray, imitate," from PIE *im-eto-, from root *aim- "copy" (cognates: Hittite himma- "imitation, substitute"). Meaning "an artificial likeness" is from c.1600. As an adjective, from 1840.