The Collaborative International Dictionary of English v.0.48:

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.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

aerofoil
    n 1: a device that provides reactive force when in motion
         relative to the surrounding air; can lift or control a
         plane in flight [syn: airfoil, aerofoil, control
         surface, surface]