oversleep—sleep beyond one’s usual or intended time for waking:
- I drove home when he never showed up only to get a call from him telling me that he’s on his way and he overslept.
sleep over—stay overnight at someone else’s home:
- I am a senior in high school and still have to ask my parents permission to sleep over at a friend’s house.
Cf.: have a sleepover—said of a party usually held by children where guests stay overnight:
- I’m planning to have a sleepover with about four girlfriends in a few weeks time (post-exam-celebration).