The Collaborative International Dictionary of English v.0.48:

Rayon \Ray"on\ (r[=a]"[o^]n), n.
   1. A synthetic fiber, made of thin filaments of regenerated
      cellulose, extruded from a solution of viscose. Called
      also viscose fiber and viscose rayon fiber.
      [PJC]

   2. a textile fabric made from rayon[1].
      [PJC]