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
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
The direct ancestor of Tyrannosaurus rex arrived in North America by crossing a land bridge from Asia 70 million years ago, the latest research suggests.
—Ashley Strickland, CNN Money, 11 May 2025
Paleontologists have long considered Tyrannosaurus rex a North American reptile, but a study now claims that the king of the dinosaurs’ predecessor hailed from the Far East.
—Paul Smaglik, Discover Magazine, 8 May 2025
Such enormous birds almost seem like a return to the Mesozoic days of giant, feathery dinosaurs, which raises the question of whether such avians could ever reach Tyrannosaurus rex sizes.
—Riley Black, Smithsonian Magazine, 6 May 2025
Kids will probably love the Naylor Family Dinosaur Gallery, which features land, sea, and sky animals of the past, including a Tyrannosaurus rex.
—Anna Halkidis, Parents, 19 Apr. 2025
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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
The direct ancestor of Tyrannosaurus rex arrived in North America by crossing a land bridge from Asia 70 million years ago, the latest research suggests.
—Ashley Strickland, CNN Money, 11 May 2025
Paleontologists have long considered Tyrannosaurus rex a North American reptile, but a study now claims that the king of the dinosaurs’ predecessor hailed from the Far East.
—Paul Smaglik, Discover Magazine, 8 May 2025
Such enormous birds almost seem like a return to the Mesozoic days of giant, feathery dinosaurs, which raises the question of whether such avians could ever reach Tyrannosaurus rex sizes.
—Riley Black, Smithsonian Magazine, 6 May 2025
Kids will probably love the Naylor Family Dinosaur Gallery, which features land, sea, and sky animals of the past, including a Tyrannosaurus rex.
—Anna Halkidis, Parents, 19 Apr. 2025
Cite this Entry
“Tyrannosaurus rex.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Tyrannosaurus%20rex. Accessed 5 Jul. 2025.
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