knock·​out | \ˈnäk-ˌau̇t \

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

(2) : technical knockout

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


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


He won the match by a knockout. He scored a knockout in the fourth round. She's a real knockout in that dress.


The Wimbledon tennis tournament is a knockout competition. a knockout sports car that's the talk of the neighborhood


the entire staff knocked itself out getting the project finished on time
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Recent Examples on the Web: Noun

There is a 31% chance that either Brazil or Germany -- both heavy favorites to win their first-round groups -- finish group runner-up, forcing a second-round knockout matchup between the two powers, according to Gracenote. Motez Bishara, CNN, "World Cup: Data says Brazil and Germany in the cards for Russia 2018," 7 June 2018 But as the 2018 Russia group stage gave way to the knockout round gave way to that penalty kick win over Colombia (Penalty kicks! Jason Gay, WSJ, "A Night on the Verge in London," 11 July 2018 The top two would advance to a knockout round of 32. Ann Killion,, "2026 World Cup jointly hosted by U.S. will be weird, watered-down — and spectacular," 10 July 2018 Vitali, now mayor of Kiev, boxed professionally from 1996-2013, his fierce jab and aggressive punching the keys to a 45-2 record with 41 knockouts. Houston Chronicle, "Vitali Klitschko honors brother in his Hall of Fame moment," 10 June 2018 Namajunas shocked then-top ranked Jedrzejczyk in November at UFC 217 via knockout to take hold of the strawweight crown. Jr Radcliffe, Milwaukee Journal Sentinel, "Milwaukee native Rose Namajunas retains strawweight title at UFC 223," 7 Apr. 2018 Croatia’s legs at the start seemed to carry the weight of so many minutes in the knockout stage, and a pressing England went up quickly. Ronald Blum,, "Croatia reaches first World Cup final," 11 July 2018 After breezing through group play, Croatia needed 120 minutes, then penalty kicks to beat both Denmark and Russia, making it just the second team to advance in a World Cup knockout stage on consecutive penalty-kick shootouts. Kevin Baxter,, "How England and Croatia match up in the World Cup semifinal," 10 July 2018 The Belgians trailed by 2-0 against Japan, the only team from Asia to reach the knockout stage in this tournament of surprises, and looked almost certain to join the ranks of big-name casualties. Tariq Panja, New York Times, "World Cup 2018: Belgium Shocks Japan With Stunning Rally," 4 July 2018

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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Statistics for knockout

Last Updated

13 Oct 2018

Look-up Popularity

Time Traveler for knockout

The first known use of knockout was in 1818

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More Definitions for knockout


knock·​out | \ˈnäk-ˌau̇t \

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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Comments on knockout

What made you want to look up knockout? Please tell us where you read or heard it (including the quote, if possible).


to clear from alleged fault or guilt

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