D defs.my
Entry 2 senses Webster, 1913

Arbitrator

/är'-bĭt-rātˌ-ẽr/ · Ar·bi·tra·tor · IPA /ˈɑrbɪtrˌeɪtər/
01 n. A person, or one of two or more persons, chosen by parties who have a controversy, to determine their differences. See Arbitration.
  1. 1.
    A person, or one of two or more persons, chosen by parties who have a controversy, to determine their differences. See Arbitration. See: Arbitration
  2. 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.