The Collaborative International Dictionary
knockout \knock"out`\, knock-out \knock"-out`\, n. Act of knocking out, or state of being knocked out; the act of rendering a person unconscious by a blow. [WordNet sense 1]
2. a blow which causes a person to become unconscious.
Syn: knockout blow, knockout punch.
3. (Boxing) the winning of a boxing contest by rendering the opponent unable to stand for a specified period, usually a count of ten; -- in contrast to a win by a decision; as, Muhammed Ali won by a knockout in the first round.
4. a strikingly beautiful woman. [Informal]
Wiktionary
n. (alternative form of knockout English)
Wikipedia
Knock-Out was the eighth Bulldog Drummond novel. It was published in 1932 and written by H. C. McNeile under the pen name Sapper.
Usage examples of "knock-out".
The second circumstance was that the promised set-to with the gloves between Hamish and his hulking challenger had resulted in a spectacular knock-out by Hamish, followed by a cheerful, unembittered relationship with the defeated Richard which Hamish found undeniably helpful.
Not long ago, it had been one of his favorite bars, a darkened den with wooden booths, a jukebox of Sinatra songs and a painting so blackened by grit that only old-timers knew it was of Joe Louis delivering the knock-out punch to Max Schmeling.
They tried to mug him, they tried to kill him, they tried knock-out drops and muscle boys-nothing worked.
They tried to mug him, they tried to kill him, they tried knock-out drops and muscle boys - nothing worked.