weapon consisting essentially of a metal tube from which a missile or projectile is shot by the force of exploding gunpowder or some other propellant. In military science, the term is often limited to cannon larger than a howitzer or mortar, although these latter two types, like all tube-fired artillery pieces, also fall within the general definition of a gun. Guns also include such military small arms as the musket, rifle, machine gun, and pistol, as well as such nonmilitary sport firearms as the shotgun. Bazookas and other rocket launchers, which launch self-propelled projectiles, are not guns, though they perform many of the same functions.

Guns of all types are treated in the Macropaedia article War, Technology of (military technology).