1. (noun)platypus, duckbill, duckbilled platypus, duck-billed platypus, Ornithorhynchus anatinus small densely furred aquatic monotreme of Australia and Tasmania having a broad bill and tail and webbed feet; only species in the family Ornithorhynchidae Synonyms: duck-billed platypus, duckbill, duckbilled platypus, platypus, paddlefish