sleeper

What is the Definition of sleeper?

Noun:

1. a rester who is sleeping
2. a spy or saboteur or terrorist planted in an enemy country who lives there as a law-abiding citizen until activated by a prearranged signal
3. an unexpected achiever of success
4. one of the cross braces that support the rails on a railway track
5. a passenger car that has berths for sleeping
6. pajamas with feet; worn by children
7. a piece of furniture that can be opened up into a bed
8. tropical fish that resembles a goby and rests quietly on the bottom in shallow water
9. an unexpected hit

Other meanings of sleeper (synonyms, cognates).