WordNet sense 1 (primitive fish of the Mississippi valley having a long paddle-shaped snout):

paddlefish, Polyodon spathula

WordNet sense 2 (small densely furred aquatic monotreme of Australia and Tasmania having a broad bill and tail and webbed feet; only species in the family Ornithorhynchidae):

platypus, duckbilled platypus, duck-billed platypus, Ornithorhynchus anatinus

WordNet sense 3 (having a beak resembling that of a duck):

duck-billed

WordNet sense 4 (having or resembling a beak):

beaked