Turret
From FreeSpace Wiki
Turrets are equiped on every military vessel, ranging from bombers to super capital ships. In FreeSpace 1, all the turrets were either standard turrets or rocket launchers, with the sole exception of two turrets on the front side of the SD Lucifer, which were beam cannons.
In FreeSpace 2, four types of turrets are feasible: Standard turret, flag gun, beam turret and warhead launcher.
The spelling 'turrent' is wrong