Tyrannosaurus rex
noun
Ty·ran·no·sau·rus rex
tə-ˌra-nə-ˈsȯr-əs-ˈreks 
(ˌ)tī-
variants
or Tyrannosaurus Rex
or less commonly Tyrannosaurus
or tyrannosaurus
or tyrannosaurus rex
plural Tyrannosaurus rexes or Tyrannosaurus Rexes also Tyrannosauruses or tyrannosauruses or tyrannosaurus rexes
: a massive North American bipedal tyrannosaurid dinosaur (Tyrannosaurus rex) of the late Cretaceous with a large skull, heavy tail, and reduced forelimbs having two clawed digits : tyrannosaur sense 1
Tyrannosaurus rex was … one of the biggest meat-eaters ever. It was over 40 feet tall, and weighed up to 7 tons!—
Wendy Larson
Wendy LarsonA study of the running ability of Tyrannosaurus Rex … suggests that the king of the prehistoric jungle wasn't quite the speedster we once thought.—Andrea Dorfman et al.
Andrea Dorfman et al.During this period, many groups of dinosaurs, including the fearsome tyrannosaurus and the three-horned triceratops, reached their greatest size, 12 meters (40 feet) and 9 meters (30 feet) long, respectively.—Joseph Wallace
Joseph Wallace… in a room full of Tyrannosaurus rexes I meet museum volunteers … who are using brushes and tiny picks on fossils in an area where people can watch and ask questions.—Mel White
Mel WhiteTrue, there may no longer be actual tyrannosauruses running amok, but there are still dinosaur descendants hanging around, and they may even be in your backyard: birds, of course!—Emily Graham
Emily Grahamcalled also T. rex
Examples of Tyrannosaurus rex in a Sentence
Recent Examples on the Web
In light of the parking lot discovery, paleontologists were inspired to go back and look at available satellite and elevation data to date all other fossils previously found within the Denver metro area, including a Tyrannosaurus rex, Triceratops and Torosaurus, and other major fossil deposits.
—Taylor Nicioli, CNN Money, 17 July 2025
Instead of snowy mountains, tropical rainforests and swampy lowland floodplains covered Colorado with dinosaurs like the Tyrannosaurus rex roaming around.
—Andrew Paul Jul 10, Popular Science, 10 July 2025
The fossil is also similar to the herbivore edmontosaurus, a larger four-legged dinosaur that roamed the region alongside fierce predators like the Tyrannosaurus rex.
—Katie Langford, Denver Post, 9 July 2025
The offerings include a Late Neolithic stone axe, the skeleton of a 150-million-year-old juvenile Ceratosaurus dinosaur, an articulated Tyrannosaurus rex foot and other fossils.
—Sarah Kuta, Smithsonian Magazine, 8 July 2025
Sue is physically the largest Tyrannosaurus rex specimen ever discovered.
—Rona Berg, Forbes.com, 27 June 2025
The crocs wandering the prehistoric Dominican Republic five million years ago were descended from carnivores that evolved back when dinosaurs like Tyrannosaurus rex still roamed the planet.
—Riley Black, Smithsonian Magazine, 25 June 2025
Paleontologists have discovered a new species of dinosaur that was related to the infamous Tyrannosaurus rex.
—Julia Jacobo, ABC News, 11 June 2025
One more migration happened as tyrannosaurs continued to evolve, and a gigantic tyrannosaur species crossed back into North America 68 million years ago, resulting in Tyrannosaurus rex, Zelenitsky said.
—Ashley Strickland, CNN Money, 11 June 2025
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Taylor Nicioli, CNN Money, 17 July 2025
Instead of snowy mountains, tropical rainforests and swampy lowland floodplains covered Colorado with dinosaurs like the Tyrannosaurus rex roaming around.
—Andrew Paul Jul 10, Popular Science, 10 July 2025
The fossil is also similar to the herbivore edmontosaurus, a larger four-legged dinosaur that roamed the region alongside fierce predators like the Tyrannosaurus rex.
—Katie Langford, Denver Post, 9 July 2025
The offerings include a Late Neolithic stone axe, the skeleton of a 150-million-year-old juvenile Ceratosaurus dinosaur, an articulated Tyrannosaurus rex foot and other fossils.
—Sarah Kuta, Smithsonian Magazine, 8 July 2025
Sue is physically the largest Tyrannosaurus rex specimen ever discovered.
—Rona Berg, Forbes.com, 27 June 2025
The crocs wandering the prehistoric Dominican Republic five million years ago were descended from carnivores that evolved back when dinosaurs like Tyrannosaurus rex still roamed the planet.
—Riley Black, Smithsonian Magazine, 25 June 2025
Paleontologists have discovered a new species of dinosaur that was related to the infamous Tyrannosaurus rex.
—Julia Jacobo, ABC News, 11 June 2025
One more migration happened as tyrannosaurs continued to evolve, and a gigantic tyrannosaur species crossed back into North America 68 million years ago, resulting in Tyrannosaurus rex, Zelenitsky said.
—Ashley Strickland, CNN Money, 11 June 2025
Cite this Entry
“Tyrannosaurus rex.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Tyrannosaurus%20rex. Accessed 25 Jul. 2025.
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