Source : Webster's Revised Unabridged Dictionary (1913)

Coscoroba \Cos`co*ro"ba\ (k?s`k?-r?"b?), n. [Native name.]
   (Zo["o]l.)
   A large, white, South American duck, of the genus
   {Cascoroba}, resembling a swan.

Source : WordNet®

coscoroba
     n : large white South American bird intermediate in some
         respects between ducks and swans