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
A 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.
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
… 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
True, 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
called also T. rex
Cite this Entry
“Tyrannosaurus rex.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Tyrannosaurus%20rex. Accessed 6 Sep. 2026.
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