A gun is a normally tubular weapon or another device designed to discharge projectiles or other materials. The projectile may be solid, liquid, gas or energy and even may be free, as with bullets and artillery shells, or captive as with Taser probes and whaling harpoons.
The means of projection varies according to design but is usually affected by the action of gas pressure, either produced through the rapid combustion of a propellant or compressed and stored by mechanical means, operating on the projectile inside an open-ended tube in the fashion of a piston. The confined gas accelerates the projectile down the length of the tube imparting sufficient velocity to sustain the projectile’s travel once the action of the gas ceases at the end of the tube or muzzle. Alternatively, acceleration via electromagnetic field generation may be employed in which case the tube may be dispensed with and a guide rail substituted.
The first devices identified as guns appeared in China around 1000AD, and by the 12th century the technology was spreading through the rest of Asia, and into Europe by the 13th century. The origin of the English word gun is presently considered to derive from the name given to a particular historical weapon.
Domina Gunilda was the name given to a remarkably large ballista, a mechanical bolt throwing weapon of huge size, mounted at Windsor Castle during the 14th century. This name in turn may have derived from the Old Norse woman’s proper name Gunnhildr which combines two Norse words referring to battle.
In any case the term gonne or gunne was applied to early hand-held firearms by the late 14th century or early 15th century.