Umpire

From Memory Alpha, the free Star Trek reference.

In the Earth sport of baseball, the umpire is the person charged with officiating the game. This includes beginning and ending the game, enforcing the rules of the game and the grounds, and making judgment calls on plays. The term is often shortened to the colloquial form "ump". They are also addressed as "blue" due to the color of the uniform some umpires wear.

Umpires are also responsible for meting out discipline to the players as a response to a rule violation. For example, touching the umpire is grounds for removal from the game, sometimes called an ejection.

In 2375, Odo served as umpire for a baseball game between the Niners and the Logicians played in the holosuite on Deep Space 9. He was forced to eject Benjamin Sisko and Solok from the game for touching him. (DS9: "Take Me Out to the Holosuite")