Bullpen (noun)

1. An area for keeping bulls, especially for breeding or for use in bullfighting.
2. An area at a baseball stadium where the relief pitchers warm up during a game.

Origin:

Mid 20th century: from bull + pen.

Examples:

1. The bull was kept in the pen before the bullfight.
2. The relief pitchers were warming up in the bullpen before the game.
3. The bullpen was the last place the team wanted to be, the starters were all winning.
4. The bull was in the pen, waiting for the bullfight to start.
5. The pitcher was warming up in the bullpen, waiting for his chance to play.