An instrument of offensive of defensive combat; something to fight with; anything used, or designed to be used, in destroying, defeating, or injuring an enemy, as a gun, a sword, etc.
- An instrument of attack or defense in combat, as a gun, missile, or sword.
- Zoology A part or organ, such as a claw or stinger, used by an animal in attack or defense.
- A means used to defend against or defeat another: Logic was her weapon.
- To supply with weapons or a weapon; arm.