The Collaborative International Dictionary of English v.0.48:

fiberglass \fiberglass\ n.
   a material made of fine glass fibers woven into a fabric-like
   form, and used in applications requiring heat resistance; it
   is also embedded in resins to make a pliable but strong
   composite material used as the main component of fishing rods
   and boat hulls, and replacing the sheet metal in some
   automobile bodies. [Also spelled fibreglass, mostly British
   in usage.]
   [WordNet 1.5] Fiberless

WordNet (r) 3.0 (2006):

fiberglass
    n 1: a covering material made of glass fibers in resins [syn:
         fiberglass, fibreglass]