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

For years, scientists believed Tyrannosaurus rex reached its adult size at around age 25.

From Science Daily • Jun. 22, 2026

To investigate the question, the researchers included 17 fossils belonging to what they describe as the "Tyrannosaurus rex species complex," a term acknowledging the possibility that more than one species or subspecies could be represented.

From Science Daily • Jun. 22, 2026

More than a century after Tyrannosaurus rex was first described by scientists, the giant predator continues to reveal new surprises.

From Science Daily • Jun. 22, 2026

After clearing that obstacle, Kyle quickly ducked left to escape the gaping jaws of a lunging Tyrannosaurus rex.

From "Mr. Lemoncello's Library Olympics" by Chris Grabenstein