Definitions from Wiktionary (knock out)

▸ verb:  To strike or render unconscious
▸ verb:  (transitive) To strike or bump (someone or something) out.
▸ verb:  (transitive, idiomatic) To render unconscious, as by a blow to the head.
▸ verb:  (transitive, informal, idiomatic) To put to sleep.
▸ verb:  (intransitive, informal, idiomatic) To fall asleep, especially suddenly.
▸ verb:  (transitive, informal, idiomatic) To exhaust.
▸ verb:  (transitive, informal, idiomatic) To impress, surpass or overwhelm (someone).
▸ verb:  (transitive, slang) To defeat or kill (someone).
▸ verb:  (transitive, idiomatic) To cause a mechanism to become non-functional by damaging or destroying it.
▸ verb:  (transitive) To eliminate from a contest or similar.
▸ verb:  (transitive) To communicate (a message) by knocking.
▸ verb:  (transitive, informal) To complete, especially in haste; knock off.
▸ verb:  To lose the scent of hounds in fox-hunting.
▸ verb:  (obsolete, Oxford University slang) To leave college after hours—after half-past ten at night when the doors have been locked.
▸ verb:  (transitive, Australia) To obtain or earn (something, often money or food).
▸ verb:  (transitive, slang, UK) To sell.

---

▸ Words similar to knock out
▸ Usage examples for knock out

▸ Idioms related to knock out
▸ Wikipedia articles (New!)
▸ Words that often appear near knock out
▸ Rhymes of knock out

▸ Invented words related to knock out