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.
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.

Origin of dinosaur

< New Latin Dinosaurus (1841), originally a genus name. See dino-, -saur
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for dinosaur

Contemporary Examples of dinosaur

Historical Examples of dinosaur

  • I don't ever want to see or taste a dinosaur steak again, he thought.

    Starman's Quest

    Robert Silverberg

  • The only complete skeleton of a dinosaur ever found was taken out in 1909.

    The Book of the National Parks

    Robert Sterling Yard

  • But they did not meet fairly, head to head, as the Dinosaur intended.

    In the Morning of Time

    Charles G. D. Roberts

  • The teeth of this horned Dinosaur resemble those of the Megalosaur.

    Extinct Monsters

    H. N. Hutchinson

  • Altogether, Triceratops is very different to any other Dinosaur.

    Extinct Monsters

    H. N. Hutchinson

British Dictionary definitions for dinosaur



any extinct terrestrial reptile of the orders Saurischia and Ornithischia, many of which were of gigantic size and abundant in the Mesozoic eraSee also saurischian, ornithischian Compare pterosaur, plesiosaur
a person or thing that is considered to be out of date
Derived Formsdinosaurian, adjective

Word Origin for dinosaur

C19: from New Latin dinosaurus, from Greek deinos fearful + sauros lizard
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for dinosaur

1841, coined in Modern Latin by Sir Richard Owen, from comb. form of Greek deinos "terrible" (see dire) + sauros "lizard" (see -saurus). Figurative sense of "person or institution not adapting to change" is from 1952.

Online Etymology Dictionary, © 2010 Douglas Harper

dinosaur in Science



Any of various extinct reptiles of the orders Saurischia and Ornithischia that flourished during the Mesozoic Era. Dinosaurs were carnivorous or herbivorous, dwelled mostly on land, and varied from the size of a small dog to the largest land animals that ever lived. One group of dinosaurs evolved into birds. See more at ornithischian saurischian. See Note at bird.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.