Define the term “aileron.”

The term "aileron" specifically refers to a control surface located on the wings of an aircraft that is crucial for managing roll during flight. The primary function of ailerons is to control the aircraft's lateral movement by increasing lift on one wing while decreasing it on the other. When the pilot moves the control yoke or stick to one side, the aileron on that wing deflects upward, decreasing lift and causing that wing to drop, while the opposite aileron deflects downward, increasing lift and raising that wing. This motion allows the aircraft to bank, making turns and maintaining stability during flight.

The other options involve different components and systems that serve distinct roles in aviation mechanics. For example, a device that measures airspeed relates to the aircraft's speed and performance but does not influence roll. Similarly, rotor control mechanisms pertain more to helicopters and their unique flight dynamics, while stabilization systems that manage pitch focus on the aircraft's vertical movement rather than lateral controls like the ailerons.