- a plant-eating dinosaur of the genus Stegosaurus, from the Jurassic and Cretaceous periods, having a heavy, bony armor and a row of bony plates along its back, and growing to a length of 20 to 40 feet (6–12 meters).
- any quadrupedal herbivorous ornithischian dinosaur of the suborder Stegosauria, esp any of the genus Stegosaurus, of Jurassic and early Cretaceous times, having an armour of bony plates
