knock out

verb knocks out · knocking out · knocked out

1. transitive To strike or bump (someone or something) out. I accidentally knocked out the glass in my picture frame.
2. idiomatic, transitive To render unconscious, as by a blow to the head. The boxer knocked out his opponent in the third round.
3. idiomatic, informal, transitive To put to sleep. The allergy pill knocked him out for a good three hours.
4. idiomatic, informal, intransitive To fall asleep, especially suddenly. That's a put-you-straight-to-sleep book if there ever was one, and I knocked right out after two paragraphs.
5. idiomatic, informal, transitive To exhaust. Running errands all day really knocked him out.
6. idiomatic, informal, transitive To impress, surpass or overwhelm (someone).
7. slang, transitive To defeat or kill (someone).
8. idiomatic, transitive To cause a mechanism to become non-functional by damaging or destroying it. The antitank gun knocked out the enemy tank.
9. transitive To eliminate from a contest or similar. As they were approaching bankruptcy from being knocked out of the calculator market, they began development on the first commercially available microcomputer, the Altair.
10. transitive To communicate (a message) by knocking. The prisoner knocked out a message on the wall for the prisoner in the adjoining cell.
11. informal, transitive To complete, especially in haste; knock off. They knocked out the entire project in one night.
12. To lose the scent of hounds in fox-hunting.
13. obsolete To leave college after hours—after half-past ten at night when the doors have been locked. "Hullo!" he said, getting up; "time for me to knock out, or old Copas will be in bed. […]"
14. Australia, transitive To obtain or earn (something, often money or food).
15. UK, slang, transitive To sell.