al·​lo·​sau·​rus ˌa-lə-ˈsȯr-əs How to pronounce allosaurus (audio)
: any of a genus (Allosaurus) of very large carnivorous North American theropod dinosaurs of the Late Jurassic period

Examples of allosaurus in a Sentence

Recent Examples on the Web It’s mounted in the Dinosaur Hall alongside the bones of an allosaurus, a contemporary predator. Corinne Purtill, Los Angeles Times, 19 Aug. 2022 In 1979, 12-year-old India Wood discovered an allosaurus skeleton on a northwest Colorado property known as Three Springs Ranch. Libertina Brandt, WSJ, 4 Oct. 2022 Big Sara, an allosaurus, was estimated at 1 million euros but sold for 3 million euros in 2020. Kristen Rogers, CNN, 12 Sep. 2022 Taylor came to see the bones, and identified them as belonging to an allosaurus. Charles Bethea, The New Yorker, 1 Oct. 2019 Discover fossils at Dinosaur National Monument, Utah Take a giant stride back 150 million years to the Jurassic era and explore the fossils of allosauruses and stegosauruses that once roamed northeastern Utah. National Geographic, 17 June 2019 But people can also bypass that completely and head right toward that violent T. rex vs. triceratops display, as well as to view other dinosaurs like the allosaurus and stegosaurus. David Oliver, USA TODAY, 5 June 2019 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'allosaurus.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


borrowed from New Latin, genus name, from allo- allo- + -saurus -saurus

Note: Genus name introduced by the American paleontologist Othniel Charles Marsh (1831-99) in "Notice of New Dinosaurian Reptiles from the Jurassic Formation," The American Journal of Science and Arts, vol. 114 (3rd series, vol. 14) (Jul.-Dec., 1877), no. 84, pp. 514-16. The combining element allo- is apparently meant to represent its distinctness: "This genus may be distinguished from any known Dinosaurs by the vertebræ, which are peculiarly modified to ensure lightness" (p. 515).

First Known Use

1886, in the meaning defined above

Time Traveler
The first known use of allosaurus was in 1886

Dictionary Entries Near allosaurus

Cite this Entry

“Allosaurus.” Dictionary, Merriam-Webster, Accessed 29 Nov. 2023.

Kids Definition


al·​lo·​sau·​rus ˌal-ə-ˈsȯr-əs How to pronounce allosaurus (audio)
: any of several very large meat-eating dinosaurs of the Jurassic period that were related to the tyrannosaur

More from Merriam-Webster on allosaurus

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!