1. A theatrical performer. 2. One who takes part; a participant: France, Britain . . . and any other external actors now involved . . . in the affairs of the continent (Helen Kitchen). 3.Law One, such as the manager of a business, who acts for another.
ETYMOLOGY:
Middle English actour, doer, probably from Latin ctor, from ctus, past participle of agere, to drive, do. See ag- in Appendix I.