Plain English Meaning

An airfoil is any specially shaped surface on an airplane that uses moving air to push or pull the airplane in a useful direction — most often, to hold the airplane up.

Full Definition

An airfoil is a surface designed to produce a useful aerodynamic reaction — primarily lift — when it moves through the air. Wings, propeller blades, horizontal and vertical stabilizers, elevators, ailerons, and rudders are all airfoils. The shape is typically curved on top and flatter on the bottom, with a rounded leading edge and a tapered trailing edge, so that air flowing around it generates a pressure difference between the upper and lower surfaces.

Context Anchor

Seen in when discussing how a makes lift and how that lift decreases when meets the at too an .