From WordNet (r) 3.0 (2006) [wn]:
halftime
n 1: an intermission between the first and second half of a game
From The Collaborative International Dictionary of English v.0.48 [gcide]:
halftime \half"time`\ n.
an intermission between the first and second half of a game,
especially a football game. Also used attributively, as the
halftime entertainment
[WordNet 1.5 +PJC] Half tone