knockout

American  

[nok-out] / ˈnɒkˌaʊt /

noun

1. an act or instance of knocking out.

2. the state or fact of being knocked out.

3. a knockout blow.

4. Informal. a person or thing overwhelmingly attractive, appealing, or successful.

5. 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.

6. Machinery. a device for knocking something loose, as finished work from a lathe chuck.

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adjective

1. that knocks out.

   the knockout punch.

knockout British  

/ ˈnɒkˌaʊt /

noun

1. the act of rendering unconscious

2. a blow that renders an opponent unconscious

3. 1. a competition in which competitors are eliminated progressively

   2. ( as modifier )

      a knockout contest

4. a series of absurd invented games, esp obstacle races, involving physical effort or skill

5. informal a person or thing that is overwhelmingly impressive or attractive

   she's a knockout

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verb

1. to render unconscious, esp by a blow

2. boxing to defeat (an opponent) by a knockout

3. to destroy, damage, or injure badly

4. to eliminate, esp in a knockout competition

5. informal to overwhelm or amaze, esp with admiration or favourable reaction

   I was knocked out by that new song

6. to remove the ashes from (one's pipe) by tapping

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.

Example Sentences

On Saturday, Fieri attended UFC 327 in Miami, where Carlos Ulberg defeated Jiří Procházka by first-round knockout to become the new UFC light heavyweight champion.

From Salon • Apr. 14, 2026

When Arsenal face Sporting in their Champions League quarter-final first leg on Wednesday, there will be much more riding on the game than just a knockout match in Lisbon.

From BBC • Apr. 6, 2026

But against Texas, a team that had dominated them during the regular season, the Bruins did all the counting as the Longhorns lay flat on their backs during an eventual knockout.

From Los Angeles Times • Apr. 4, 2026

In January, Google used a U.S. court order to aim a knockout blow at Ipidea.

From The Wall Street Journal • Apr. 3, 2026

“He’s breathing, so that’s good. It’s like he got hit with a knockout juju.”

From "The Manifestor Prophecy" by Angie Thomas

Related Words

• technical knockout