self-defense
Americannoun
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the act of defending one's person when physically attacked, as by countering blows or overcoming an assailant.
the art of self-defense.
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a claim or plea that the use of force or injuring or killing another was necessary in defending one's own person from physical attack.
He shot the man who was trying to stab him and pleaded self-defense at the murder trial.
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an act or instance of defending or protecting one's own interests, property, ideas, etc., as by argument or strategy.
Other Word Forms
Etymology
Origin of self-defense
First recorded in 1645–55
Explanation
When you protect yourself forcefully against an attack, that's self-defense. If you kicked a dog that tried to bite you, you don't need to feel bad: it was self-defense. The act of defending yourself, protecting yourself from being physically harmed, is self-defense. You can take a class to learn tactics of self-defense; many martial arts can be used this way, to fend off an attacker. Self-defense is also a legal right — by law, people can use "reasonable force" to defend their own lives. Self-defense was originally a sporting term, first used in fencing and then in boxing.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
It’s hard to say, though within hours then-Homeland Security Secretary Kristi Noem claimed the ICE agent fired in self-defense.
From The Wall Street Journal ● Sep. 9, 2026
One member of the self-defense militia had accidentally shot himself in the foot.
From Los Angeles Times ● Sep. 6, 2026
Plus, the House of Mouse was already changing up its rhetorical tack to mount a fulsome self-defense on free speech and free press grounds.
From Slate ● Aug. 18, 2026
The island opens up about American role in training troops for self-defense.
From The Wall Street Journal ● Aug. 5, 2026
“Mom and I talked about it. I’m going to take self-defense classes. Not because I want to fight him, but Mom thinks it’ll help with my confidence. Maybe I’ll meet some new friends.”
From "The Parker Inheritance" by Varian Johnson
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
