From WordNet (r) 2.0 (August 2003) [wn]:
half-time
adj : involving half the standard or customary time for an
activity; "he had two years of half-time training"
adv : for less than the standard number of hours; "he works
part-time" [syn: part-time] [ant: full-time]
From WordNet (r) 2.0 (August 2003) [wn]:
halftime
n : 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