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a person or thing that is considered to be out of date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
- dinosaurian adjective
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.
Specimens once believed to represent a miniature species of armored dinosaur have now been identified as young ankylosaurs.
From Science Daily • Apr. 21, 2026
This approach had not previously been applied to dinosaur fossils and could open up new ways to study fragmentary remains.
From Science Daily • Apr. 15, 2026
The dinosaur had large cheekbones, a broad braincase, and likely a short, deep snout.
From Science Daily • Apr. 15, 2026
For him, the film — like all dinosaur media — has the potential to do something new, outside of timeworn franchises.
From Salon • Apr. 12, 2026
“I mean—the fertilizer in the mail slot. It was supposed to be dinosaur poop.”
From "Linked" by Gordon Korman
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.
