WordNet (r) 3.0 (2006):

cutting edge
    n 1: the position of greatest importance or advancement; the
         leading position in any movement or field; "the Cotswolds
         were once at the forefront of woollen manufacturing in
         England"; "the idea of motion was always to the forefront
         of his mind and central to his philosophy" [syn:
         vanguard, forefront, cutting edge]
    2: the sharp cutting side of the blade of a knife [syn: knife
       edge, cutting edge]