The Collaborative International Dictionary of English v.0.48:

Crinoline \Crin"o*line\ (kr?n"?-l?n), n. [F., fr. crin hair,L.
   crinis.]
   1. A kind of stiff cloth, used chiefly by women, for
      underskirts, to expand the gown worn over it; -- so called
      because originally made of hair.
      [1913 Webster]

   2. A lady's skirt made of any stiff material; latterly, a
      hoop skirt.
      [1913 Webster]

WordNet (r) 3.0 (2006):

crinoline
    n 1: a skirt stiffened with hoops [syn: hoopskirt,
         crinoline]
    2: a full stiff petticoat made of crinoline fabric
    3: a stiff coarse fabric used to stiffen hats or clothing