knockout
Americannoun
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an act or instance of knocking out.
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the state or fact of being knocked out.
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a knockout blow.
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Informal. a person or thing overwhelmingly attractive, appealing, or successful.
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a panel in a casing, can, or box, especially of metal or plastic, so designed that it can readily be removed, as by punching, hammering, or cutting, to provide an opening into the interior.
a knockout in a junction box.
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Machinery. a device for knocking something loose, as finished work from a lathe chuck.
adjective
noun
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the act of rendering unconscious
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a blow that renders an opponent unconscious
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a competition in which competitors are eliminated progressively
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( as modifier )
a knockout contest
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a series of absurd invented games, esp obstacle races, involving physical effort or skill
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informal a person or thing that is overwhelmingly impressive or attractive
she's a knockout
verb
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to render unconscious, esp by a blow
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boxing to defeat (an opponent) by a knockout
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to destroy, damage, or injure badly
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to eliminate, esp in a knockout competition
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informal to overwhelm or amaze, esp with admiration or favourable reaction
I was knocked out by that new song
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to remove the ashes from (one's pipe) by tapping
Other Word Forms
Noun Inflected Forms
Etymology
Origin of knockout
1810–20; 1935–40 knockout for def. 4; noun, adj. use of verb phrase knock out
Explanation
In the sport of boxing, a knockout is a blow that sends one of the boxers to the mat, unable to continue fighting. If you are down and can't rise before the ref counts to ten, consider it a knockout. In full-contact fighting sports, including boxing, karate, and kickboxing, the ultimate goal is a match-winning knockout of the opponent. Not all boxing matches end this way, but a knockout is the most exciting (and dangerous) way for a match to end. This word is also used to mean "gorgeous person," so if someone tells you you're a knockout, you can be sure they mean it as a compliment.
Vocabulary lists containing knockout
World Cup Vocabulary
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"Amigo Brothers" and "Lean on Me"
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All My Sons
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
England's place in the knockout stages of the World Cup has been confirmed before they face Panama in their final group game on Saturday.
From BBC • Jun. 27, 2026
Then the United States took care of Australia 2-0 on June 19 without Pulisic to secure their place in knockout play.
From Los Angeles Times • Jun. 26, 2026
It is a debate that will rumble on into the summer, with Scotland's chances of knockout progression now rated at about 5%.
From BBC • Jun. 26, 2026
But it will need him in the knockout stage.
From Los Angeles Times • Jun. 26, 2026
Probably a knockdown or a knockout, he thought; maybe the brash kid had made good his boast.
From "145th Street: Short Stories" by Walter Dean Myers
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Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.