1
: a plea of justification for the use of force or for homicide
2
: the act of defending oneself, one's property, or a close relative

Examples of self-defense in a Sentence

Recent Examples on the Web
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The National Shooting Sports Foundation has estimated that close to half of the 11 million Americans who bought a first-time firearm for shooting sports, self-defense, and hunting during 2020 and 2021 were women. — Heide Brandes, Condé Nast Traveler, 28 Oct. 2026 Gomes said that Gallardo had been acting in self-defense and was protecting his wife when the shooting occurred. — CBS News, 28 Oct. 2026 No criminal charges have been filed, and federal officials said Good’s shooter acted in self-defense. — Hannah Schoenbaum, Los Angeles Times, 23 Oct. 2026 Several members of self-defense groups were also injured by gunfire, according to local media reports. — Jacqueline Charles, Miami Herald, 21 Oct. 2026 See All Example Sentences for self-defense

Word History

First Known Use

1609, in the meaning defined at sense 2

Time Traveler
The first known use of self-defense was in 1609

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Cite this Entry

“Self-defense.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/self-defense. Accessed 1 Nov. 2026.

Kids Definition

self-defense

noun
self-de·​fense
ˌself-di-ˈfen(t)s
: the act of defending oneself, one's property, or a close relative

Legal Definition

self-defense

noun
self-de·​fense
ˈself-di-ˈfens
1
: the use of force to defend oneself
2
: an affirmative defense (as to a murder charge) alleging that the defendant used force necessarily to protect himself or herself because of a reasonable belief that the other party intended to inflict great bodily harm or death see also justification sense 2

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