self-defence

noun

1. the act of defending one’s person when physically attacked, as by countering blows or overcoming an assailant: the art of self-defense.
2. 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.
3. an act or instance of defending or protecting one’s own interests, property, ideas, etc., as by argument or strategy.

noun

1. the act of defending oneself, one’s actions, ideas, etc
2. boxing as a means of defending the person (esp in the phrase noble art of self-defence)
3. law the right to defend one’s person, family, or property against attack or threat of attack by the use of no more force than is reasonable

n.1650s, “act of defending oneself,” first attested in Hobbes, from self- + defense. In sports sense, first with reference to fencing (1728), then boxing (1820s).