noun a place on a baseball field where relief pitchers can warm up during a game.
noun a large cell where prisoners (people awaiting trial or sentence or refugees or illegal immigrants) are confined together temporarily.
— synonyms: detention_cell, detention_centre
Examples
“Magnus and Big Buck are over in the bullspen, ready for tonight's rodeo.”
“After that hit, there is activity in the bullpen.”
“Their bullpen is worn out after yesterday's doubleheader where both games went 12 innings.”