defense (American English) and defence (British English and Canadian English) can refer to any of the following:
- For defense of a doctoral dissertation see thesis committee
- For the military term see defense (military)
- civil defense measures and emergency preparedness
- In politics, defense may be a euphemism for war. See, for example, the United States Department of Defense.
- For legal defense see defense (legal)
- For defense in sport see defense (sport)