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.
For generations, our nation’s reigning political culture has celebrated armed self-defense as a fundamental right.
From Slate • Jun. 4, 2026
The Cuban government said in a statement that the 1996 shootdown was "legitimate self-defense" against an airspace violation.
From Barron's • May 21, 2026
"Put simply, the self-defense system becomes more resilient. Hormones conducive to tissue repair and regeneration may be released and promote the self-healing system's functioning."
From Science Daily • May 4, 2026
Japan renounced war after its defeat in World War II, though it maintains capable and well-equipped armed forces for self-defense.
From The Wall Street Journal • Apr. 21, 2026
In one of the asides that probably prepared us for the job better than any of the approved curriculum items, Kirkley said that occasionally officers did have to act in self-defense.
From "Newjack: Guarding Sing Sing" by Ted Conover
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.
