Meaning in English apparently developed from "calculate," to "calculate with a view to action, plan," then to "direct a missile, a blow, etc." (late 14c.). Also used in Middle English of directing a letter, planting an altar, pitching a tent. Intransitive sense "intend, attempt" (early 14c.) was used by Shakespeare but is now considered colloquial. Related: Aimed; aiming.
Proto-Indo-European root meaning "to copy."
It is the hypothetical source of/evidence for its existence is provided by: Latin imago "image," aemulus "emulous," imitari "to copy, portray, imitate;" Hittite himma- "imitation, substitute."
1520s, from French imitateur (14c.) or directly from Latin imitator "a copyist; a mimic," from imitari "to copy, imitate" (from PIE root *aim- "to copy").
1550s, from French imitable (16c.), from Latin imitabilis "that may be imitated," from imitari "to copy, portray" (from PIE root *aim- "to copy"). Related: Imitability.
c. 1400, "emulation; act of copying," from Old French imitacion, from Latin imitationem (nominative imitatio) "a copying, imitation," noun of action from past participle stem of imitari "to copy, portray, imitate," from PIE *im-eto-, from root *aim- "to copy." Meaning "an artificial likeness" is from c. 1600. As an adjective, from 1840.
"faculty of the mind which forms and manipulates images," mid-14c., ymaginacion, from Old French imaginacion "concept, mental picture; hallucination," from Latin imaginationem (nominative imaginatio) "imagination, a fancy," noun of action from past participle stem of imaginari "to form an image of, represent"), from imago "an image, a likeness," from stem of imitari "to copy, imitate" (from PIE root *aim- "to copy")