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]WordNet (r) 3.0 (2006):
leading edge n 1: forward edge of an airfoil