For the acronym CAP, see CAP.

Cap can mean:

• Cap, a headgear
• An upper bound, for example a tax cap
• Bottle cap, a device to seal glass bottles
• Camper shell, a type of caravan
• Cap (sport), awarded in some sports when a player represents his country
• Capacitor, in electronics slang
• Capping inversion, in meteorology
• Capricornus (constellation), standard astronomical abbreviation
• A common nickname of marvel comics' Captain America
• Caspar Weinberger, his nickname
• Interest rate cap, in the context of interest rate derivatives
• Percussion cap, a small amount of percussion-sensitive explosive, held in a tape or small cup
• Pipe cap, a pipe fitting used to seal the end of a pipe
• A small, powdered compound used to make noise and smoke in a cap gun.
• A crown (dentistry) is sometimes called a cap.
• A slang term for shooting someone, or alternately, to insult someone. The term derives from the practice of knee-capping. The usage determines the meaning. To 'cap someone' means to shoot them. To 'cap on someone' means to insult them.
• Capturing the flag.