knock·​out | \ ˈnäk-ˌau̇t How to pronounce knockout (audio) \

Definition of knockout

 (Entry 1 of 3)

1a : the act of knocking out : the condition of being knocked out
b(1) : the termination of a boxing match when one boxer has been knocked down and is unable to rise and resume boxing within a specified time
c : a blow that knocks out an opponent
2 : a sensationally striking, appealing, or attractive person or thing



Definition of knockout (Entry 2 of 3)

1 : causing a knockout a knockout blow
2 : sensationally striking, appealing, or attractive a knockout dress
3 : having all or part of a gene eliminated or inactivated by genetic engineering knockout mice predisposed to diabetes mellitus

knock out

knocked out; knocking out; knocks out

Definition of knock out (Entry 3 of 3)

transitive verb

1 : to produce roughly or hastily
2a(1) : to defeat (a boxing opponent) by a knockout
(2) : to make unconscious the drug knocked him out
b : to make inoperative or useless electricity was knocked out by the storm
c : to get rid of : eliminate knocked out illegal gambling
3 : to tire out : exhaust knocked themselves out with work
4 : to cause (an opposing pitcher) to be removed from a baseball game by a batting rally

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Examples of knockout in a Sentence

Noun He won the match by a knockout. He scored a knockout in the fourth round. She's a real knockout in that dress. Adjective The Wimbledon tennis tournament is a knockout competition. a knockout sports car that's the talk of the neighborhood Verb the entire staff knocked itself out getting the project finished on time
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Recent Examples on the Web: Noun Reiss allowed the knockout to be scored by the judges but docked Paul two points, despite not being warned for the fouls, the outlet reported. Eric Todisco,, "YouTube Stars Logan Paul and KSI Face Off in Boxing Match — See Who Won the Showdown," 11 Nov. 2019 The frock's high-leg slit gave the perfect peek-a-boo moment for her knockout footwear: a pair of knee-high, zebra haircalf heeled boots by Khaite (these bad boys currently retail at a whopping $1,800). Chelsey Sanchez, Harper's BAZAAR, "Katie Holmes Is a Goddess in a Slinky Silver Dress and Zebra-Print Boots," 7 Nov. 2019 Only in knockout competition does a whole campaign usually come down to the final fixture, but the 2014/15 Serie A season threw up one of these rare occasions, where the previous 37 games faded into the background ahead of the final royal rumble., "Napoli 2-4 Lazio: The 90 Minute Champions League Shootout That Had it All," 6 Nov. 2019 Miranda's musical, with knockout choreography by Andy Blankenbuehler, carries us from American independence into the Jefferson administration. Jim Higgins, Milwaukee Journal Sentinel, "Fast-paced, forceful 'Hamilton' lives up to its ambitions at Milwaukee's Marcus Center," 24 Oct. 2019 Kovalev has one of the sport’s best jabs, but has gone 4-3 in has last seven fights, including two losses to Andre Ward and a knockout loss to Eleider Alvarez last year. Manouk Akopyan, Los Angeles Times, "Canelo Alvarez looking to crush Sergey Kovalev, win title in fourth division," 23 Oct. 2019 Yet the defense provided the knockout when Trevon Diggs returned a fumble 99 yards to go up 22 when the Vols were threatening to cut it to an eight point game midway through the fourth quarter. Michael Casagrande |, al, "Instant analysis: Alabama lights up Tennessee after Tua injury," 20 Oct. 2019 Middleweight boxer Patrick Day has died days after suffering traumatic brain injuries in a brutal knockout loss, his promoter said Wednesday. Fox News, "Boxer Patrick Day, 27, dies days after brutal KO," 17 Oct. 2019 This also means that the restaurant lacks a knockout entree-sized meat dish. Nick Kindelsperger,, "New Indian restaurant Superkhana subverts traditions: You can’t order rice, but there are flatbread tacos and butter chicken calzones," 9 Oct. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'knockout.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of knockout


1887, in the meaning defined at sense 1a


1818, in the meaning defined at sense 1


1856, in the meaning defined at sense 1

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Time Traveler for knockout

Time Traveler

The first known use of knockout was in 1818

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Statistics for knockout

Last Updated

24 Nov 2019

Cite this Entry

“Knockout.” The Dictionary, Merriam-Webster Inc., Accessed 5 December 2019.

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More Definitions for knockout


How to pronounce knock out (audio)

English Language Learners Definition of knockout

 (Entry 1 of 2)

: an occurrence in which a boxing match ends when a fighter has been knocked down by a punch and is unable to start fighting again before 10 seconds have passed
informal : a very attractive or appealing person or thing



English Language Learners Definition of knockout (Entry 2 of 2)

: causing someone to become unconscious
informal : extremely attractive or appealing
British, of a contest or competition : designed so that winning teams or players continue to play and losing teams or players do not


knock·​out | \ ˈnäk-ˌau̇t How to pronounce knockout (audio) \

Medical Definition of knockout

: having all or part of a gene eliminated or inactivated by genetic engineering knockout mice predisposed to diabetes mellitus serve as animal models in the study of human diabetes

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