1. To be unsuccessful in retaining possession of; mislay: He's always losing his keys on the way out the door.
2. a. To come to be deprived of the ownership, care, or control of (something one has had), as by negligence, accident, or theft: I've lost three umbrellas this year. Britain lost its American colonies in a revolution. b. To be deprived of (something one has had): lost their lives; lost her youth through hardship. c. To be bereaved of: lost his wife. d. To be unable to keep alive: a doctor who has lost very few patients.
3. To be unable to maintain, sustain, or keep: lost everything in the stock market crash; is losing supporters by changing his mind.
4. To fail to win; fail in: lost the game; lost the court case.
5. To fail to use or take advantage of: Don't lose a chance to improve your position.
6. To fail to hear, see, or understand: We lost the plane in the fog. I lost her when she started speaking about thermodynamics.
7. a. To let (oneself) become unable to find the way. b. To remove (oneself), as from everyday reality into a fantasy world.
8. To rid oneself of: lost five pounds.
9. To consume aimlessly; waste: lost a week in idle occupations.
10. To stray or wander from: lose one's way.
11. a. To elude or outdistance: lost their pursuers. b. To be outdistanced by: chased the thieves but lost them.
12. To become slow by (a specified amount of time). Used of a timepiece.
13. To cause or result in the loss of: Failure to reply to the advertisement lost her the job.
14. To cause to be destroyed. Usually used in the passive: Both planes were lost in the crash.
15. To cause to be damned.