someone with the power to settle matters at will
"she was the final arbiter on all matters of fashion"
someone chosen to judge and decide a disputed issue
"the critic was considered to be an arbiter of modern literature"
"the arbitrator's authority derived from the consent of the disputants"
"an umpire was appointed to settle the tax case"
A person appointed, or chosen, by parties to determine a controversy between them; an arbitrator.
To act as arbiter.