gun

gun in general, any weapon that discharges shot, shells, or bullets by the explosion of gunpowder or some other explosive from a straight tube. See firearm ; artillery ; small arms .

gun n.
1. a weapon incorporating a metal tube from which bullets, shells, or other missiles are propelled by explosive force, typically making a characteristic loud, sharp noise.

2. a gunman: a hired gun.

3. (guns) slang, dated used as a nickname for a ship's gunnery officer.

4. the firing of a piece of artillery as a salute or signal: the boom of the one o'clock gun echoed across the river.
v. gunned, gunning (gun someone down) shoot someone with a gun: they were gunned down by masked snipers.

gun Tubular weapon firing a projectile, usually by force of explosion. The term is now restricted to artillery pieces with a relatively high muzzle velocity and a flat trajectory. Pistols, rifles and machine guns are usually described as guns; mortars and howitzers are not.