defense

American  

[dih-fens, dee-fens] / dɪˈfɛns, ˈdi fɛns /

noun

1. resistance against attack; protection.

   Two more regiments are needed for the defense of the city.

   Synonyms:

   safeguard, security

2. something that guards against harm, such as a fortification, physical or mental quality, or medication.

   This fort was once the main defense of the island.

3. the support of a cause or the like by speech, argument, etc..

   He spoke in defense of the nation's foreign policy.

   Synonyms:

   justification, advocacy, support

4. a speech, argument, etc., in vindication.

   She delivered a defense of free enterprise.

5. Law.

   1. the denial or pleading of the defendant in answer to the claim or charge that has been made.

   2. the proceedings adopted by a defendant or the defendant's legal agents, for defending against the charges that have been made.

   3. a defendant and their counsel.

6. Psychology. defense mechanism.

7. Sports.

   1. the practice or art of shielding oneself or one's goal from attack, as in fencing, boxing, soccer, or football.

   2. the team attempting to thwart the attack of the team having the ball or puck.

   3. the players of a team who line up in their own defensive zone.

   4. the positions on the field, ice, etc., taken by such players.

8. Also called Defense Department.  (initial capital letter) the Department of Defense.

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verb (used with object)

defensed, defensing

1. Sports. to defend against (an opponent, play, or tactic).

Other Word Forms

Derived Forms

• nondefense
  noun
• defenseless
  adjective
• predefense
  noun
• defenselessly
  adverb
• defenselessness
  noun
• undefensed
  adjective

Etymology

Origin of defense

First recorded in 1250–1300; Middle English from Old French from Late Latin dēfēnsa “a forbidding,” noun use of feminine of past participle of Latin dēfendere “to defend ”; replacing Middle English defens, from Anglo-French, Old French, from Medieval Latin defēnsum “(thing) forbidden,” neuter past participle of Latin dēfendere

Explanation

Defense has to do with protecting something or fighting against an opponent, whether it's national defense, a football team's defense, or a defense lawyer. Defense is the opposite of offense. It has to do with defending against all sorts of things: In the military, defense is about protecting a country from attack. In sports, defense is supposed to stop the other team from scoring. A defense attorney tries to prove his client is innocent. A defense can even be an excuse for doing something, as in "In my own defense, I was sleepwalking at the time."

Example Sentences

But it acts all-powerful, seeming to know more about outer-space tech than its overseers at the Department of Defense.

From Los Angeles Times • Jun. 10, 2026

SpaceX, a Defense Department service provider, is proceeding with its IPO, with trading expected to begin on Friday.

From Barron's • Jun. 10, 2026

Yet, all these wars carry a similar lesson, Italian Defense Minister Guido Crosetto said in an interview.

From The Wall Street Journal • Jun. 10, 2026

Meanwhile, despite Anthropic's ongoing lawsuit against the US Department of Defense over its refusal to accept government use of its AI tools, US government agencies have been testing Mythos too.

From BBC • Jun. 9, 2026

The whole of Harry’s Defense Against the Dark Arts class was miserable about his resignation.

From "Harry Potter And The Prisoner Of Azkaban" by J.K. Rowling