home Marina Bezzi dinosaur di⋅no⋅saur [dahy-nuh-sawr] –noun 1. any chiefly terrestrial, herbivorous or carnivorous reptile of the extinct orders Saurischia and Ornithischia, from the Mesozoic Era, certain species of which are the largest known land animals. 2. something that is unwieldy in size, anachronistically outmoded, or unable to adapt to change: The old steel mill was a dinosaur that cost the company millions to operate. d a b c d e f g h i j k l m n o p q r s t u v w x y z difficult doo-dz diffuse dilemma dinosaur disarray dog distance divided doily dirt dismantle dining-room