Turret (noun)

1. A small tower, typically one projecting from a larger structure, such as a castle or fort, and often used for defensive or decorative purposes.
2. A rotating structure on top of a vehicle, such as a tank or aircraft, that carries weapons.

Origin:

Middle english: from old french torrette, diminutive of tor "tower", from latin turris.

Examples:

1. The castle had a round turret with a spiral staircase inside.
2. The tank's turret was equipped with a powerful gun.
3. The turrets of the medieval castle were used as lookout posts.
4. The battleship had several turrets, each with its own set of guns.
5. The turret on the fighter aircraft was used to aim and fire its weapons.