umpire

Noun

• 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
    

• an official at a baseball game

Verb

• be a referee or umpire in a sports competition

Related words

• Synonyms: 
  arbiter , arbitrator , ump , referee