The Collaborative International Dictionary of English v.0.48:

Marabou \Mar`a*bou"\ (m[a^]r"[.a]b[=oo]"), n. [F.]
   1. (Zool.) A large black-and-white carrion-eating stork of
      the genus Leptoptilos (formerly Ciconia), esp. the
      African species (Leptoptilus crumeniferus syn.
      Leptoptilos crumenifer), whose downy under-wing feathers
      are used to trim garments; called also marabout. The
      Asiatic species (Leptoptilos dubius, or Leptoptilos
      argala) is the adjutant. See Adjutant. [Written also
      marabu.]
      [1913 Webster]

   2. One having five eighths negro blood; the offspring of a
      mulatto and a griffe. [Louisiana] --Bartlett.
      [1913 Webster]

   3. A kind of thrown raw silk, nearly white naturally, but
      capable of being dyed without scouring; also, a thin
      fabric made from it, as for scarfs, which resembles the
      feathers of the marabou in delicacy, -- whence the name.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

Leptoptilus crumeniferus
    n 1: large African black-and-white carrion-eating stork; its
         downy underwing feathers are used to trim garments [syn:
         marabou, marabout, marabou stork, Leptoptilus
         crumeniferus]