WordNet (r) 3.0 (2006):

time off
    n 1: a time period when you are not required to work; "he
         requested time off to attend his grandmother's funeral"
         [ant: work time]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "time off":
   alternate, break, coffee break, cover, do a hitch, do a stint,
   do a tour, do time, downtime, enlist, fill in for, furlough,
   half time, half-time intermission, have a go, have tenure,
   hold office, holiday, interim, interlude, intermezzo, intermission,
   intermittence, interregnum, interruption, interval, keep a watch,
   leave, leave of absence, letup, liberty, lull, off-time,
   paid holiday, paid vacation, pause, plateau, point of repose,
   quiet spell, re-up, recess, reenlist, relief, relieve, respite,
   resting point, sabbatical, sabbatical leave, sabbatical year,
   serve time, shore leave, sign up, spell, spell off, take turns,
   time out, vacation, weekend