- a person chosen to decide a dispute or settle differences, especially one formally empowered to examine the facts and decide the issue.
early 15c., from Old French arbitratour (13c.), from Latin arbitrator “a spectator, hearer, witness, judge,” agent noun from past participle stem of arbitrari, from arbiter (see ). The legal form of popular arbiter; in modern usage, an arbiter makes decisions of his own accord and is accountable to no one but himself; an arbitrator (early 15c.) decides issues referred to him by the parties.