The Collaborative International Dictionary of English v.0.48:

Oversleep \O`ver*sleep"\, v. t.
   To sleep beyond; as, to oversleep one's self or one's usual
   hour of rising.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Oversleep \O`ver*sleep"\, v. i.
   To sleep too long.
   [1913 Webster]

WordNet (r) 3.0 (2006):

oversleep
    v 1: sleep longer than intended

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "oversleep":
   be behindhand, be late, be overdue, blow the chance, doze, drowse,
   get up late, keep everyone waiting, keep late hours,
   lose the chance, lose the opportunity, miss an opportunity,
   miss the boat, miss the chance, nap, neglect the opportunity,
   saw logs, saw wood, show up late, sleep, sleep soundly, slumber,
   snore, stay late, stay up late, take a nap