In FTC®, turrets refer to mechanisms that allow for yaw (side-to-side) rotation of another mechanism. This is typically done for the purpose of positioning an intake or scoring mechanism. For example, a shooter could be mounted on a turret to allow for aiming without turning the robot. Turrets typically have a gear, sprocket, or pulley mounted to them, which motors and servos use to rotate them.
The FTC community often splits these turrets into 2 categories, “full turrets” and “mini turrets.” Full turrets are typically those powered by motors or multiple servos at the base of the robot, and move large mechanism(s), and what the lone word “turret” generally refers to. Mini turrets are typically powered by one or two servos, are located at the end of an extension of some sort, and only pivot an end effector.