verb, lost, los⋅ing.| 1. | to come to be without (something in one's possession or care), through accident, theft, etc., so that there is little or no prospect of recovery: I'm sure I've merely misplaced my hat, not lost it. |
| 2. | to fail inadvertently to retain (something) in such a way that it cannot be immediately recovered: I just lost a dime under this sofa. |
| 3. | to suffer the deprivation of: to lose one's job; to lose one's life. |
| 4. | to be bereaved of by death: to lose a sister. |
| 5. | to fail to keep, preserve, or maintain: to lose one's balance; to lose one's figure. |
| 6. | (of a clock or watch) to run slower by: The watch loses three minutes a day. |
| 7. | to give up; forfeit the possession of: to lose a fortune at the gaming table. |
| 8. | to get rid of: to lose one's fear of the dark; to lose weight. |
| 9. | to bring to destruction or ruin (usually used passively): Ship and crew were lost. |
| 10. | to condemn to hell; damn. |
| 11. | to have slip from sight, hearing, attention, etc.: to lose him in the crowd. |
| 12. | to stray from or become ignorant of (one's way, directions, etc.): to lose one's bearings. |
| 13. | to leave far behind in a pursuit, race, etc.; outstrip: She managed to lose the other runners on the final lap of the race. |
| 14. | to use to no purpose; waste: to lose time in waiting. |
| 15. | to fail to have, get, catch, etc.; miss: to lose a bargain. |
| 16. | to fail to win (a prize, stake, etc.): to lose a bet. |
| 17. | to be defeated in (a game, lawsuit, battle, etc.): He has lost very few cases in his career as a lawyer. |
| 18. | to cause the loss of: The delay lost the battle for them. |
| 19. | to let (oneself) go astray, miss the way, etc.: We lost ourselves in the woods. |
| 20. | to allow (oneself) to become absorbed or engrossed in something and oblivious to all else: I had lost myself in thought. |
| 21. | (of a physician) to fail to preserve the life of (a patient). |
| 22. | (of a woman) to fail to be delivered of (a live baby) because of miscarriage, complications in childbirth, etc. |
| 23. | to suffer loss: to lose on a contract. |
| 24. | to suffer defeat or fail to win, as in a contest, race, or game: We played well, but we lost. |
| 25. | to depreciate in effectiveness or in some other essential quality: a classic that loses in translation. |
| 26. | (of a clock, watch, etc.) to run slow. |
| 27. | lose out, to suffer defeat or loss; fail to obtain something desired: He got through the preliminaries, but lost out in the finals. |
| 28. | lose face. face (def. 48). |

lose jargon
(MIT) 1. To fail. A program loses when it encounters an exceptional condition or fails to work in the expected manner.
2. To be exceptionally unesthetic or crocky.
3. Of people, to be obnoxious or unusually stupid (as opposed to ignorant).
4. Refers to something that is losing, especially in the phrases "That's a lose!" and "What a lose!"
[The Jargon File]
(1995-04-19)
lose
In addition to the idioms beginning with lose, also see get (lose) one's bearings; keep (lose) one's cool; keep (lose) track; win some, lose some. Also see under losing; lost.