The Collaborative International Dictionary of English v.0.48:

Ornithorhynchus \Or`ni*tho*rhyn"chus\, prop. n. [NL., fr. Gr.
   'o`rnis, 'o`rniqos, a bird + ? snout, beak.] (Zool.)
   A genus of monotremes including the platypus (Ornithorhyncus
   anatinus). See Duck mole, under Duck.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Ornithorhynchus
    n 1: type genus of the family Ornithorhynchidae [syn:
         Ornithorhynchus, genus Ornithorhynchus]