knock out

verb16

1. •
   To strike or render unconscious
2. •
   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. — 1980
3. •
   (slang) To defeat or kill (someone).
4. •
   To render unconscious, as by a blow to the head.

   • The boxer knocked out his opponent in the third round.
5. •
   (informal) To put to sleep.

   • The allergy pill knocked him out for a good three hours.
6. •
   (informal) 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. — 2014
7. •
   To cause a mechanism to become non-functional by damaging or destroying it.

   • The antitank gun knocked out the enemy tank.
8. •
   (informal) To exhaust.

   • Running errands all day really knocked him out.
9. •
   To strike or bump (someone or something) out.

   • I accidentally knocked out the glass in my picture frame.
10. •
    (informal) To complete, especially in haste; knock off.

    • They knocked out the entire project in one night.
11. •
    (informal) To impress, surpass or overwhelm (someone).
12. •
    To communicate (a message) by knocking.

    • The prisoner knocked out a message on the wall for the prisoner in the adjoining cell.
13. •
    (UK, slang) To sell.
14. •
    (Australia) To obtain or earn (something, often money or food).
15. •
    To lose the scent of hounds in fox-hunting.
16. •
    (no longer used) 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. […]" — 1861