Aileron

n.	1.	A half gable, as at the end of a penthouse or of the aisle of a church.
	2.	(Aëronautics) A small plane or surface capable of being manipulated by the pilot of a flying machine to control lateral balance; a hinged wing tip; a lateral stabilizing or balancing plane.

Noun

1.

aileron - an airfoil that controls lateral motion

aerofoil, airfoil, control surface, surface, wing