When someone in authority arbitrates between two people or groups who are in dispute, they consider all the facts and make an official decision about who is right. He arbitrates between investors and members of the association The tribunal had been set up to arbitrate in the dispute. + arbitrator arbitrators ar·bi·tra·tor He served as an arbitrator in a series of commercial disputes in India. to officially judge how an argument between two opposing sides should be settled arbitrate between (past participle of arbitrari, from arbiter; ARBITER)