dinosaur
Americannoun
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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.
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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.
noun
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any extinct terrestrial reptile of the orders Saurischia and Ornithischia, many of which were of gigantic size and abundant in the Mesozoic era See also saurischian ornithischian Compare pterosaur plesiosaur
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a person or thing that is considered to be out of date
Other Word Forms
Etymology
Origin of dinosaur
< New Latin Dinosaurus (1841), originally a genus name. See dino-, -saur
Explanation
If you've ever seen Jurassic Park, you know that dinosaurs were large reptilian creatures that walked the earth during the Mesozoic era that ran from 245 million to 68 million years ago and included the Triassic, Jurassic, and Cretaceous periods. The ancient Greeks had no knowledge of dinosaurs that we know of, but they unknowingly contributed to the word dinosaur. It was cobbled together in 1841 by British scientist Sir Richard Own, using the words deinos, meaning "terrible" and sauros meaning "lizard." All are gone—at least in their original form, although it is thought they simply evolved into other, present-day animals. The word dinosaur is often used for someone who is old-fashioned or unable to adapt to modern times.
Vocabulary lists containing dinosaur
Tyrannosaurus Lex(icon)
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Paleontology: Dinosaurs - Introductory
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Paleontology: Dinosaurs - Middle School and High School
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
It has since been donated to the Badlands Dinosaur Museum in Dickinson, North Dakota.
From Science Daily • May 5, 2026
Dinosaur fans had been speculating about the existence of prehistoric creatures in “The End of Oak Street” for months before the world had any proper confirmation.
From Salon • Apr. 12, 2026
Today, the town calls itself “the Dinosaur Capital of British Columbia.”
From The Wall Street Journal • Feb. 16, 2026
After more than three decades making memories for generations of children, the owners of Tenby's Dinosaur Park have decided to retire.
From BBC • Oct. 7, 2025
“Yeah, we could call it the World’s Greatest Dinosaur War Ever,” I said, “but I get to be the Americans.”
From "The Watsons Go to Birmingham" by Christopher Paul Curtis
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
