Tyrannosaurus rex
Americannoun
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.
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
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
One of the most famous discoveries came in 2005, when paleontologist Mary Schweitzer and colleagues reported soft tissue structures inside a Tyrannosaurus rex fossil.
From Science Daily • May 14, 2026
To explore the issue further, the new study examined 17 specimens within what researchers describe as the "Tyrannosaurus rex species complex."
From Science Daily • Mar. 5, 2026
Scientists believe it rivalled the fearsome Tyrannosaurus rex in size, measuring around 40 feet long with a 20-inch sword-like crest on its head.
From Barron's • Feb. 27, 2026
It was found alongside a tooth from a Tyrannosaurus rex and a jawbone from a crocodylian, in a region already known for fossils of the duck-billed dinosaur Edmontosaurus.
From Science Daily • Dec. 15, 2025
The notable exception being the Tyrannosaurus rex, which was found by Barnum Brown in 1902.
From "A Short History of Nearly Everything" by Bill Bryson
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.
