Plain English Meaning
A small flap near the front of the wing that helps smooth out the airflow when the aircraft is flying fast enough that shock waves are starting to form.
Full Definition
A small auxiliary flap mounted on the forward portion of a transonic or supersonic airfoil, used to modify the flow of air over the leading area of the wing in order to delay or weaken shock wave formation and improve handling at high subsonic and transonic speeds.
Context Anchor
Seen in aerodynamics discussions about , , and how manage airflow in subsonic and .