The term FOUL-BALL CALLER refers to an umpire, which is a three-letter word. An umpire is an official in a variety of sports who is responsible for enforcing the rules and maintaining the order of the game. They are also responsible for making decisions on plays that are not clear cut, such as whether a ball was fair or foul. Umpires are usually positioned behind home plate in baseball games, and they are the ones who make the call when a ball is hit out of bounds.