The Collaborative International Dictionary of English v.0.48:

Chiffon \Chif`fon"\, n. [F., lit., rag. See Chiffonier.]
   1. Any merely ornamental adjunct of a woman's dress, as a
      bunch of ribbon, lace, etc.
      [Webster 1913 Suppl.]

   2. A kind of soft gauzy material used for ruches, trimmings,
      etc.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

chiffon
    n 1: a sheer fabric of silk or rayon