Source : Webster's Revised Unabridged Dictionary (1913)

Rhea \Rhe"a\, n. [L., a proper name.] (Zo["o]l.)
   Any one of three species of large South American ostrichlike
   birds of the genera {Rhea} and {Pterocnemia}. Called also the
   {American ostrich}.

   Note: The common rhea, or nandou ({Rhea Americana}), ranges
         from Brazil to Patagonia. Darwin's rhea ({Pterocnemia
         Darwinii}), of Patagonia, is smaller, and has the legs
         feathered below the knee.