knock·out
ˈnäk-ˌau̇t 
1
a
: 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)
c
: a blow that knocks out an opponent
2
: a sensationally striking, appealing, or attractive person or thing
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
knocked out; knocking out; knocks out
1
: to produce roughly or hastily
2
a(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
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
Recent Examples on the Web
Liam Twomey, New York Times, 9 May 2025
Think vaulted ceilings, stone fireplaces, wraparound porches, and a dining room with knockout water views.
—Abby Montanez, Robb Report, 7 May 2025
Liam Tharme, New York Times, 13 Apr. 2025
Even if Germany beats Colombia, a knockout path of Japan then either of those would be much better than facing Spain at any point.
—Tribune News Service, Orlando Sentinel, 23 July 2024
Trent Reinsmith, Forbes.com, 10 May 2025
The crash knocked out information from radars located at an FAA facility in Westbury, New York, where the air traffic controllers formerly managed flights heading to Newark.
—Pete Muntean, CNN Money, 10 May 2025
See All Example Sentences for knockout
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Noun
The fact Maresca felt secure enough to make either selection — in the Conference League knockout stage, no less — underlines the total lack of jeopardy Chelsea have encountered on their road to the final in Wroclaw, save for one nervy second half in their qualifier against Servette back in August.
—Liam Twomey, New York Times, 9 May 2025
Think vaulted ceilings, stone fireplaces, wraparound porches, and a dining room with knockout water views.
—Abby Montanez, Robb Report, 7 May 2025
Adjective
Arteta understandably is more risk-averse in knockout European ties, but Premier League matches sometimes need to be forcibly opened up — even at the risk of fatigue or becoming defensively compromised.
—Liam Tharme, New York Times, 13 Apr. 2025
Even if Germany beats Colombia, a knockout path of Japan then either of those would be much better than facing Spain at any point.
—Tribune News Service, Orlando Sentinel, 23 July 2024
Verb
The 28-year-old got to finishing fights in his most recent outing, knocking out former UFC welterweight title challenger Gilbert Burns in the third round of their UFC 299 meeting.
—Trent Reinsmith, Forbes.com, 10 May 2025
The crash knocked out information from radars located at an FAA facility in Westbury, New York, where the air traffic controllers formerly managed flights heading to Newark.
—Pete Muntean, CNN Money, 10 May 2025
See All Example Sentences for knockout
Cite this Entry
“Knockout.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/knockout. Accessed 18 May. 2025.
Copy CitationKids Definition
knockout
1 of 2 noun
knock·out
ˈnäk-ˌau̇t
1
: the act of knocking out : the condition of being knocked out
2
: something or someone very striking or attractive
knockout
adjective
knock out
2 of 2 verbˈnäk-ˈau̇t,
näk-ˈau̇t
: to make unconscious
Medical Definition
knockout
adjective
knock·out
ˈnäk-ˌau̇t
: 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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