Definition of knockout
(Entry 1 of 3)
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
knockout
adjectiveDefinition 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
verbknocked out; knocking out; knocks out
Definition of knock out (Entry 3 of 3)
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
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Test Your Vocabulary
Words of Snow and Ice Quiz
- Which of the following refers to thin, bending ice, or to the act of running over such ice?

Test your knowledge - and maybe learn something along the way.
TAKE THE QUIZ
Anagram puzzles meet word search.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridgedWords at Play
Ask the Editors
Word Games
Words of Snow and Ice Quiz
A selection of words from the chillier parts of t...
Take the quizName that Thing: Toys and Games Edition
It's all fun and games until someone beats your h...
Take the quizTrue or False?
Test your knowledge - and maybe learn something a...
Take the quizSCRABBLE® Sprint
SCRABBLE® fans, sharpen your skills!
Play the game
Share knockout
Time Traveler for knockout
The first known use of knockout was in 1818
See more words from the same year