Source : Webster's Revised Unabridged Dictionary (1913)

Aerofoil \A"["e]r*o*foil`\, n. [A["e]ro- + foil.]
   A plane or arched surface for sustaining bodies by its
   movement through the air; a spread wing, as of a bird.

Source : WordNet®

aerofoil
     n : a device that provides reactive force when in motion
         relative to the surrounding air; can lift or control a
         plane in flight [syn: {airfoil}, {control surface}, {surface}]