The term 'OFFICIAL BEHIND A CATCHER' is referring to an umpire, which is a three-letter acronym, UMP. An umpire is an official in the sport of baseball who is responsible for making decisions on the field. They are positioned behind the catcher and have the authority to make calls on balls and strikes, fair or foul balls, and other rulings. Umpires also have the power to eject players, coaches, and other personnel from the game.