Source : Webster's Revised Unabridged Dictionary (1913)

Hadrosaurus \Had`ro*sau"rus\, 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.

Source : WordNet®

hadrosaurus
     n : any of numerous large bipedal ornithischian dinosaurs having
         a horny duck-like bill and webbed feet; may have been
         partly aquatic [syn: {hadrosaur}, {duck-billed dinosaur}]