Noun

1. A person who keeps something.

   Finders keepers; losers weepers.

2. Someone or something worth keeping.

   You can throw out all the blurry photos, but the one with her and her daughter is certainly a keeper.

3. A person charged with guarding or caring for, storing, or maintaining something; a custodian, a guard.
4. The player charged with guarding a goal or wicket. Short form of goalkeeper, wicketkeeper.
5. A part of a mechanism that catches or retains another part, for example the part of a door lock that fits in the frame and receives the bolt.
6. An offensive play in which the quarterback runs toward the goal with the ball after it is snapped.