late 14c. "to carry into effect" (transitive, mostly in law with reference to warrants, sentences, etc.), also "carry out or accomplish a course of action" (intransitive), from Old French executer (14c.), from Medieval Latin executare, from Latin execut-/exsecut-, past participle stem of exequi/exsequi "to follow out, to follow to the grave," figuratively "to follow, follow after, accompany, follow up, prosecute, carry out, enforce; execute, accomplish; punish, avenge," from ex- "out" (see ex-) + sequi "follow" (from PIE root *sekw- (1) "to follow"). Meaning "to inflict capital punishment" is from late 15c., from earlier legal sense "perform judgment or sentence on" (early 15c.). Related: Executed; executing.