(n) any of numerous large bipedal ornithischian dinosaurs having a horny duck-like bill and webbed feet; may have been partly aquatic, Syn.hadrosaurus, duck-billed dinosaur
‖n. [ NL., fr. Gr. "adro`s thick + say^ros lizard.] (Paleon.) An American herbivorous dinosaur of great size, allied to the iguanodon. It is found in the Cretaceous formation. [1913 Webster]