A gun turret is a weapon mount that protects the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in many directions. The turret is also a rotating weapon platform. This platform can be mounted on a fortified building or structure such as an anti-naval land battery, or on a combat vehicle, a naval ship, or a military aircraft.
Turrets may be armed with one or more machine guns, automatic cannons, large-calibre guns, or missile launchers. It may be manned or remotely controlled, and is often armoured. A small turret, or sub-turret on a larger one, is called a cupola. The term cupola also describes rotating turrets that carry no weapons but instead sighting devices, as in the case of tank commanders. A finial is an extremely small sub-turret or sub-sub-turret mounted on a cupola turret.
The protection provided by the turret may be against battle damage, or against the weather conditions and general environment in which the weapon or its crew will be operating. The term comes from the pre-existing noun turret—a self-contained protective position which is situated on top of a fortification or defensive wall, as opposed to rising directly from the ground, when it constitutes a tower.