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
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
Sixty-six million years ago, the end-Cretaceous extinction eliminated the Tyrannosaurus rex and the velociraptor; rapid climate change from an asteroid impact was the likely cause.
—D. T. Max, New Yorker, 7 Apr. 2025
Charlotte Burke, 7, a second-grader from Vernon Hills, had a photo opportunity with the Tyrannosaurus rex with the youngster’s head inside the dinosaur’s mouth.
—Karie Angell Luc, Chicago Tribune, 7 Apr. 2025
New dinosaur discovery may be the closest relative to Tyrannosaurus rex, scientists say
The findings will also help researchers enhance the understanding of macroevolution and how species adapted to specific environments over time, according to the paper.
—Julia Jacobo, ABC News, 18 Feb. 2025
The traveling dinosaur show includes animatronic dinosaurs ranging from Apatosaurus to Tyrannosaurus rex, recreated by paleontologists.
—Del Mar Times, San Diego Union-Tribune, 14 Jan. 2025
Using Tyrannosaurus rex as a model, paleontologists have estimated that much more massive dinosaurs are still awaiting discovery.
—Riley Black, Smithsonian Magazine, 16 Dec. 2024
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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
Sixty-six million years ago, the end-Cretaceous extinction eliminated the Tyrannosaurus rex and the velociraptor; rapid climate change from an asteroid impact was the likely cause.
—D. T. Max, New Yorker, 7 Apr. 2025
Charlotte Burke, 7, a second-grader from Vernon Hills, had a photo opportunity with the Tyrannosaurus rex with the youngster’s head inside the dinosaur’s mouth.
—Karie Angell Luc, Chicago Tribune, 7 Apr. 2025
New dinosaur discovery may be the closest relative to Tyrannosaurus rex, scientists say
The findings will also help researchers enhance the understanding of macroevolution and how species adapted to specific environments over time, according to the paper.
—Julia Jacobo, ABC News, 18 Feb. 2025
The traveling dinosaur show includes animatronic dinosaurs ranging from Apatosaurus to Tyrannosaurus rex, recreated by paleontologists.
—Del Mar Times, San Diego Union-Tribune, 14 Jan. 2025
Using Tyrannosaurus rex as a model, paleontologists have estimated that much more massive dinosaurs are still awaiting discovery.
—Riley Black, Smithsonian Magazine, 16 Dec. 2024
Cite this Entry
“Tyrannosaurus rex.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Tyrannosaurus%20rex. Accessed 14 May. 2025.
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