- (transitive) To strike or bump (someone or something) out.
- I accidentally knocked out the glass in my picture frame.
- (transitive, idiomatic) To render unconscious, as by a blow to the head.
- The boxer knocked out his opponent in the third round.
- (transitive, idiomatic) To put to sleep.
- The allergy pill knocked him out for a good three hours.
- (transitive, idiomatic) To exhaust.
- Running errands all day really knocked him out.
- (transitive, idiomatic) To complete, especially in haste; knock off.
- They knocked out the entire project in one night.
- (transitive, idiomatic) To cause a mechanism to become non-functional by damaging or destroying it.
- The antitank gun knocked out the enemy tank.
- (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.
- (transitive) To communicate (a message) by knocking.
- The prisoner knocked out a message on the wall for the prisoner in the adjoining cell.
strike or bump something out
render someone unconscious