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
Derived 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.
Federal officials said the deadly shooting was an act of self defense.
From Los Angeles Times • Jan. 11, 2026
The reality is that his life was endangered and he fired in self defense.
From Salon • Jan. 9, 2026
Southwell herself says she owns guns primarily for self defense and that she is seeing a dramatic increase in women wanting guns for the same reason.
From Los Angeles Times • Apr. 11, 2024
A San Francisco jury found a homeless man not guilty of assault charges Friday after the defendant argued he acted in self defense when he beat a former fire department official with a metal pipe.
From Washington Times • Dec. 24, 2023
Let me urge in self defense that if life in France bubbles, it occasionally leaves a bitter taste in the mouth.
From The Silent Barrier by Tracy, Louis
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.
