Source : Webster's Revised Unabridged Dictionary (1913)

Actor \Ac"tor\, n. [L. actor, fr. agere to act.]
   1. One who acts, or takes part in any affair; a doer.

   2. A theatrical performer; a stageplayer.

            After a well graced actor leaves the stage. --Shak.

   3. (Law)
      (a) An advocate or proctor in civil courts or causes.
          --Jacobs.
      (b) One who institutes a suit; plaintiff or complainant.

Source : WordNet®

actor
     n 1: a theatrical performer [syn: {histrion}, {player}, {thespian},
           {role player}]
     2: a person who acts and gets things done; "he's a principal
        actor in this affair"; "when you want something done get a
        doer"; "he's a miracle worker" [syn: {doer}, {worker}]

Source : Free On-Line Dictionary of Computing

actor
     
        1.  In {object-oriented} programming, an {object}
        which exists as a {concurrent} process.
     
        2.  In {Chorus}, the unit of resource
        allocation.
     
        (1994-11-08)

Actor
     
         An {object-oriented} language for {Microsoft
        Windows} written by Charles Duff of the {Whitewater Group} ca.
        1986.  It has {Pascal}/{C}-like {syntax}.  Uses a
        {token-threaded} {interpreter}.  {Early binding} is an option.
     
        ["Actor Does More than Windows", E.R. Tello, Dr Dobb's J
        13(1):114-125 (Jan 1988)].
     
        (1994-11-08)