The Collaborative International Dictionary of English v.0.48:

Polyurethane \Pol"y*ur`eth*ane\, n. (Chem.)
   any polymer containing [-NH.CO.O-] linkages; such polymers
   are much used as the basis of light but rigid foams for
   packaging (

   polyurethane foam) and for hard coatings, as on floors.
      [PJC]

WordNet (r) 3.0 (2006):

polyurethane
    n 1: any of various polymers containing the urethane radical; a
         wide variety of synthetic forms are made and used as
         adhesives or plastics or paints or rubber [syn:
         polyurethane, polyurethan]