Source : Webster's Revised Unabridged Dictionary (1913)

Arbitrator \Ar"bi*tra`tor\, n. [L., fr. arbitrari: cf. F.
   arbitrateur.]
   1. A person, or one of two or more persons, chosen by parties
      who have a controversy, to determine their differences.
      See {Arbitration}.

   2. One who has the power of deciding or prescribing without
      control; a ruler; a governor.

            Though Heaven be shut, And Heaven's high Arbitrators
            sit secure.                           --Milton.

            Masters of their own terms and arbitrators of a
            peace.                                --Addison.

   Syn: Judge; umpire; referee; arbiter. See {Judge}.

Source : WordNet®

arbitrator
     n : someone chosen to judge and decide a disputed issue [syn: {arbiter}]