There are multiple definitions - click on the translation that matches your context.

árbitro

substantivo

full

umpire

noun

Definitions of umpire

English

a person who is appointed to resolve a dispute

Arbitration must proceed before PEC's arbitrator and an umpire selected by him.

English

a person who watches a game or a sport closely to make sure that the rules are being followed correctly and to enforce those rules

In 1974, the Major League Baseball Players Association ranked Harvey as the National League's best umpire.