Source : Webster's Revised Unabridged Dictionary (1913)

Platypus \Plat"y*pus\, n. [NL., fr. Gr. ? + ? foot.] (Zo["o]l.)
   The duck mole. See under {Duck}.

Source : WordNet®

platypus
     n : small densely furred aquatic monotreme of Australia and
         Tasmania having a broad bill and tail and webbed feet;
         only species in the family Ornithorhynchidae [syn: {duckbill},
          {duckbilled platypus}, {duck-billed platypus}, {Ornithorhynchus
         anatinus}]