Synonyms for Platypus (same or very similar meaning)
WordNet sense 1 (small densely furred aquatic monotreme of Australia and Tasmania having a broad bill and tail and webbed feet; only species in the family Ornithorhynchidae):
duckbill, duckbilled platypus, duck-billed platypus, Ornithorhynchus anatinusFrom the ODE community, based on WordNetadd/edit