Tyrannosaurus rex

American  

[ti-ran-uh-sawr-uhs reks, tahy‐] / tɪˌræn əˈsɔr əs ˈreks, taɪ‐ /

Also T. rex

noun

Tyrannosaurus rexes plural

1. tyrannosaur.

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Tyrannosaurus rex Cultural  

1. A large, carnivorous (see carnivore) dinosaur that walked on two legs. Its name is from the Greek words meaning “tyrant” and “lizard” and the Latin word for “king.”

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Usage

What is a Tyrannosaurus rex? Tyrannosaurus rex was a giant, meat-eating dinosaur that walked on two legs and had a long tail and a big head with sharp teeth (and, yes, two little arms). The name Tyrannosaurus rex comes from the Greek words tyranno (“tyrant”) and saurus (“lizard”) and the Latin word rex (“king”). So, Tyrannosaurus rex means something like “king of the tyrant lizards.” It is commonly called T. rex for short. The name is fitting: Tyrannosaurus rex is one of the largest land predators that has ever lived. It was the largest of the tyrannosaurs, reaching a length of 47 feet (14. 3 m) or more. People often list the T. rex as their favorite dinosaur, and its popularity has grown through many pop culture depictions, such as its appearances in the Jurassic Park series of movies and books. However, to be scientifically precise about it, the T. rex lived during the Late Cretaceous period, about 90–65 million years ago, around the end of the age of dinosaurs.

Other Word Forms

Noun Inflected Forms

• Tyrannosaurus rexes
  plural

Etymology

Origin of Tyrannosaurus rex

First recorded in 1905–10; New Latin Tyrannosaurus, the genus name; see tyrannosaur ( def. ) + Latin rex “king”; see rex ( def. )

Example Sentences

One of the world's most complete Tyrannosaurus rex skeletons, nicknamed "Gus," was showcased Wednesday at Sotheby's auction house in New York ahead of its sale later this month.

From Barron's • Jul. 1, 2026

My research team and I identified preserved blood vessels in a Tyrannosaurus rex fossil, and our findings were recently published in Scientific Reports.

From Science Daily • Apr. 26, 2026

"At the time, the prevailing consensus was that the Nanotyrannus holotype skull represented an immature Tyrannosaurus rex, and was not a separate species," said Griffin, assistant professor of geosciences at Princeton.

From Science Daily • Apr. 15, 2026

"This lets us be confident in keeping the name Nanotyrannus, because this animal is clearly not on a growth path to becoming a Tyrannosaurus rex."

From Science Daily • Apr. 15, 2026

I’m not even sure why Crenshaw was a cat, and not a dog or an alligator or a Tyrannosaurus rex with three heads.

From "Crenshaw" by Katherine Applegate