Gun turret
A gun turret (or simply turret) is a mounting platform from which weapons can be fired that affords protection, visibility, and the ability to turn and aim. A modern gun turret is generally a rotatable weapon mount that houses the crew or mechanism of a projectile-firing weapon and, at the same time, lets the weapon be aimed and fired in some degree of azimuth and elevation (cone of fire)[ Online Etymology Dictionary].
Rotating gun turrets protect the weapon and its crew as they rotate. When this meaning of the word "turret" started being used, turrets were typically cylindrical. Barbettes were an alternative to turrets; with a barbette, the protection was fixed, and the weapon and crew were on a rotating platform inside the barbette. In the 1890s, armored hoods were added to barbettes; these rotated with the platform. By the early 20th Century, these hoods were known as turrets.
The protection provided by the turret may be against battle damage, weather conditions, general environment in which the weapon or its crew will be operating. The name derives from the pre-existing noun turret, from the French "touret", diminutive of the word "tower," meaning a self-contained protective position that is situated on top of a fortification or defensive wall as opposed to rising directly from the ground, in which case it constitutes a tower [Barnaby, p.23].
Gun turret. Online Etymology Dictionary. Retrieved from: https://www.etymonline.com/word/turret
Barnaby, K.C., (1968). Some ship disasters and their causes.Paris:Hutchinson.