leading edge

from WordNet (r) 3.0 (2006)

leading edge
    n 1: forward edge of an airfoil

from The Collaborative International Dictionary of English v.0.48

Leading edge \Lead"ing edge\n.
   1. (Aeronautics) the front edge of an airfoil; same as
      {{Advancing edge}}, above.
      [Webster 1913 Suppl.]

   2. the front edge of anything that moves; also used
      metaphorically, as the leading edge in art. See also
      {cutting edge}.
      [PJC]