Back"stop` (?), n. 1. In baseball, a fence, prop. at least 90 feet behind the home base, to stop the balls that pass the catcher; also, the catcher himself.

2. In rounders, the player who stands immediately behind the striking base.

3. In cricket, the longstop; also, the wicket keeper.

Back"stop` (?), n. 1. In baseball, a fence, prop. at least 90 feet behind the home base, to stop the balls that pass the catcher; also, the catcher himself.

2. In rounders, the player who stands immediately behind the striking base.

3. In cricket, the longstop; also, the wicket keeper.

• (baseball): A Wooden wall with a fence over it that is behind homebase in a baseball game.
  
• A device that prevents locomotive cars from rolling off a railroad track.