Source : Webster's Revised Unabridged Dictionary (1913)

Stegosauria \Steg`o*sau"ri*a\, n. pl. [NL. See {Stegosaurus}.]
   (Paleon.)
   An extinct order of herbivorous dinosaurs, including the
   genera {Stegosaurus}, {Omosaurus}, and their allies.

Stegosaurus \Steg`o*sau"rus\, n. [NL., fr. Gr. ? roof + ? a
   lizard.] (Paleon.)
   A genus of large Jurassic dinosaurs remarkable for a powerful
   dermal armature of plates and spines.

Source : WordNet®

stegosaurus
     n : herbivorous ornithischian dinosaur with a row of bony plates
         along its back and a spiked tail probably used as a
         weapon [syn: {stegosaur}, {Stegosaur stenops}]