knock out

knock out (third-person singular simple present knocks out, present participle knocking out, simple past and past participle knocked out)

1. (transitive) To strike or bump (someone or something) out.

   I accidentally knocked out the glass in my picture frame.

2. (transitive, idiomatic) To render unconscious, as by a blow to the head.

   The boxer knocked out his opponent in the third round.

   • 1918, W. B. Maxwell, chapter 22, in The Mirror and the Lamp:

     In the autumn there was a row at some cement works about the unskilled labour men. A union had just been started for them and all but a few joined. One of these blacklegs was laid for by a picket and knocked out of time.

3. (transitive, idiomatic) To put to sleep.

   The allergy pill knocked him out for a good three hours.

4. (transitive, idiomatic) To exhaust.

   Running errands all day really knocked him out.

5. (transitive, idiomatic) To complete, especially in haste; knock off.

   They knocked out the entire project in one night.

6. (transitive, idiomatic) To cause a mechanism to become non-functional by damaging or destroying it.

   The antitank gun knocked out the enemy tank.

7. (sports) To eliminate.
   • 2011 December 15, Marc Higginson, “Shamrock Rovers 0-4 Tottenham”, in BBC Sport:

     Tottenham were knocked out of the Europa League, despite a comfortable victory over Shamrock Rovers in Dublin.

8. (transitive) To communicate (a message) by knocking.

   The prisoner knocked out a message on the wall for the prisoner in the adjoining cell.

9. To lose the scent of hounds in fox-hunting.

• don't knock yourself out
• knock one out
• knock oneself out

• knockout