D defs.my
Entry 2 senses Webster, 1913

bullpen

/(bụl"pĕn`)/ · bull·pen · IPA /bˈʊlpˌɛn/
01 n. an open area in a baseball stadium, off the playing field, where pitchers may warm up by throwing a number of trial pitches before playing.
  1. 1.
    an open area in a baseball stadium, off the playing field, where pitchers may warm up by throwing a number of trial pitches before playing.(Baseball)
  2. 2.
    the relief pitchers on a baseball team. Contrasted with starters.[collective]