Other forms: arbitrators
An arbitrator is someone who helps resolve a dispute. If you and your sibling are butting heads over whose turn it is to clean the bathroom, you may need the assistance of an arbitrator.
In legal terms, an arbitrator is the impartial judge of a case settled outside of a courtroom. Their job is to carefully consider both sides and make a decision, without the expense and time involved in going before an actual judge or jury. As a neutral decider whose decision is authoritative, an umpire or referee is another good example of an arbitrator. The Latin root of arbitrator is arbiter, "judge."