The Collaborative International Dictionary of English v.0.48:

Bombycinous \Bom*byc"i*nous\ (b[o^]m*b[i^]s"[i^]*n[u^]s), a. [L.
   bombycinus. See Bombazine.]
   1. Silken; made of silk. [Obs.] --Coles.
      [1913 Webster]

   2. Being of the color of the silkworm; transparent with a
      yellow tint. --E. Darwin.
      [1913 Webster]