firearm

n. weapon from which a projectile is discharged by means of gunpowder (i.e. rifle, pistol)

A firearm is a device that can be used as a weapon that fires either single or multiple projectiles propelled at high velocity by the gases produced through rapid, confined burning of a propellant. This process of rapid burning is technically known as deflagration. In older firearms, this propellant was typically black powder, but modern firearms use smokeless powder, cordite, or other propellants. Most modern firearms (with the notable exception of smoothbore shotguns) have rifled barrels to impart spin to the projectile for improved flight stability.
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Noun
1. a portable gun; "he wore his firearm in a shoulder holster"
(synonym) piece, small-arm
(hypernym) gun
(hyponym) autoloader, self-loader
(part-meronym) firing pin

Any weapon (including a starter gun) which will or is designed to or may readily be converted to expel a projectile by the action of an explosive; the frame or receiver of any such weapon; any firearm muffler or firearm silencer; or any destructive device. 18 U.S.C.

Synonyms and related words:
automatic, blowgun, blowpipe, flamethrower, gat, gun, handgun, heater, musket, peashooter, piece, pistol, repeater, revolver, rifle, rod, sawed-off shotgun, shooting iron, shotgun, six-gun, six-shooter