noun.
A weapon, especially a pistol or rifle, capable of firing a projectile and using an explosive charge as a propellant.
The Century Dictionary and Cyclopedia
noun.
A weapon from which a missile, such as a bullet, cannon-ball, shell, etc., is expelled by the combustion of gunpowder or other similar explosive. Pistols, muskets, cannon, etc., are firearms.
the GNU version of the Collaborative International Dictionary of English
noun.
A gun, pistol, or any weapon from which a shot is discharged by the force of an explosive substance, as gunpowder.