The Collaborative International Dictionary of English v.0.48:

aeroplane \aer"*o*plane`\ aeroplane \a"["e]r*o*plane`\, n.
   [a["e]ro- + plane.] (A["e]ronautics)
   1. A light rigid plane used in a["e]rial navigation to oppose
      sudden upward or downward movement in the air, as in
      gliding machines; specif., such a plane slightly inclined
      and driven forward as a lifting device in some flying
      machines. Also called airfoil.
      [Webster 1913 Suppl.]

   2. Hence: A heavier-than-air flying machine using such a
      device to provide lift; an airplane. In a modern
      aeroplane, the airfoils are called the wings, and most
      of the lift is derived from these surfaces. In contrast to
      helicopters, the wings are fixed to the passenger
      compartment (airframe) and do not move relative to the
      frame; thus such a machine is called a fixed-wing
      aircraft. These machines are called monoplanes, biplanes,
      triplanes, or quadruplanes, according to the number of
      main supporting planes (wings) used in their construction.
      After 1940 few planes with more than one airfoil were
      constructed, and these are used by hobbyists or for
      special purposes. Being heavier than air they depend for
      their levitation on motion imparted by the thrust from
      either propellers driven by an engine, or, in a jet plane,
      by the reaction from a high-velocity stream of gases
      expelled rearward from a jet engine. They start from the
      ground by a run on small wheels or runners, and are guided
      by a steering apparatus consisting of horizontal and
      vertical movable planes, which usually form part of the
      wings or tail. There are many varieties of form and
      construction, which in some cases are known by the names
      of their inventors. In U.S., an aeroplane is usually
      called an airplane or plane.
      [Webster 1913 Suppl. +PJC]

The Collaborative International Dictionary of English v.0.48:

airfoil \air"foil`\ n.
   1. 1 a surface such as the wing of an airplane designed to
      provide reactive force when in motion relative to the
      surrounding air.

   Syn: aerofoil
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

airfoil
    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]