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

Keep scrolling for more

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
See More
Recent Examples on the Web: Noun The knockout rounds will shift to Sydney on Thursday. Ben Rothenberg, New York Times, "As Fires Spread, So Do Player Concerns Ahead of the Australian Open," 3 Jan. 2020 The top eight teams in the group stage would enter the knockout round of the tournament. Jamie Goldberg, oregonlive, "NBA sends teams proposal for 78-game regular season, in-season tournament for 2021-22 season," 21 Dec. 2019 Today is the group stages; varsity teams are seeded against one another to determine who will play in the marquee knockout round, which will be broadcasted live on Twitch. Luke Winkie, The Atlantic, "Where Gamers Are the Only Varsity Athletes," 13 Nov. 2019 Familiar names Bayern Munich, Juventus, and Paris Saint-Germain won to take their usual places in the knockout rounds . ., "College Basketball," 7 Nov. 2019 Lampard will be determined to cut out the defensive lapses from his side before their decisive fixtures against Valencia and Lille, as the Blues aim to progress through their tough group and into the knockout rounds of the Champions League., "Chelsea Enter Rarified Air With Astonishing Champions League Comeback Against Ajax," 6 Nov. 2019 But that didn’t help last year when visiting Real Salt Lake scored on its only two shots on goal, then added a third score on a freak own goal, to eliminate LAFC in the knockout round. Kevin Baxter, Los Angeles Times, "Soccer! Nations League may be a waste of time for the U.S.," 15 Oct. 2019 The field of 10 candidates will be winnowed down in a series of knockout rounds before a head-to-head showdown between the top two finishers. Fox News, "How Britain's Conservatives will choose their next leader," 13 June 2019 The first four teams in the two five-team groups advance to the knockout stage . ., "was announced as the AP’s female athlete of the decade.," 31 Dec. 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.

See More

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

Keep scrolling for more

Learn More about knockout

Time Traveler for knockout

Time Traveler

The first known use of knockout was in 1818

See more words from the same year

Statistics for knockout

Last Updated

20 Jan 2020

Cite this Entry

“Knockout.” The Dictionary, Merriam-Webster Inc., Accessed 26 January 2020.

Keep scrolling for more

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

Keep scrolling for more

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 express in a more acceptable way

Get Word of the Day daily email!

Test Your Vocabulary

Intact Latin Quiz

  • roman tablet
  • What did focus mean in Latin?
Spell It

Can you spell these 10 commonly misspelled words?

Bee Cubed

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!