bullpen [bool′pen΄ ]
1. a fenced enclosure for bulls
2. Informal a large room or enclosure for a number of people; specif., a barred enclosure in a jail, where prisoners are kept together temporarily, as between their arrest and the placing of charges
3. Baseball
a) an area near the playing field, where relief pitchers practice and warm up
b) the relief pitchers of one team

English World dictionary. . 2014.