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a. Any of various extinct terrestrial reptiles of the orders Saurischia and Ornithischia that existed during the Mesozoic Era, including both carnivores and herbivores and often reaching a gigantic size.
b. Any of various other large extinct reptiles, such as an ichthyosaur.
2. A relic of the past: "living dinosaurs of the world of vegetation" (John Olmsted).
3. One that is hopelessly outmoded or unwieldy: "The old, big-city teaching hospital is a dinosaur" (Peggy Breault).
[New Latin Dīnosauria, group name, from Dīnosaurus, former genus name : Greek deinos, monstrous + Greek sauros, lizard.]
di′no·saur′i·an (-sôr′ē-ən) n. & adj.
di′no·sau′ric (-sôr′ĭk) adj.
(Palaeontology) of, like, or relating to dinosaurs