as·​ter·​oid | \ ˈa-stə-ˌrȯid How to pronounce asteroid (audio) \

Definition of asteroid

 (Entry 1 of 2)

1 : any of the small rocky celestial bodies found especially between the orbits of Mars and Jupiter



Definition of asteroid (Entry 2 of 2)

1 : resembling a star asteroid bodies in sporotrichosis
2 : of or resembling a starfish

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Other Words from asteroid


asteroidal \ ˌa-​stə-​ˈrȯi-​dᵊl How to pronounce asteroidal (audio) \ adjective

Examples of asteroid in a Sentence

Noun Most asteroids are found between Mars and Jupiter.
Recent Examples on the Web: Noun Then, one day 66 million years ago, a catastrophic asteroid impact triggered a devastating mass extinction that killed off nearly all dinosaurs—leaving only birds—and reshuffled the evolutionary deck for mammals. Riley Black, Smithsonian, "Fossil Site Reveals How Mammals Thrived After the Death of the Dinosaurs," 25 Oct. 2019 Known as Lucy, the mission will explore the Trojans, asteroids that share an orbit with Jupiter. David Grossman, Popular Mechanics, "Sounds Like We're Close to Exploring Jupiter's Crazy-Old Asteroids," 24 Oct. 2019 And, in that, McConnell may find utility to entertaining the impeachment asteroid that seems inevitable to wind up on his side of the Capitol. Philip Elliott, Time, "Why Mitch McConnell Could Be Key In the Trump Impeachment Battle," 26 Sep. 2019 Science and finance collided when FinTwit (Finance Twitter) made good-natured fun of the idea that a gold-laden asteroid could make everyone on Earth rich. David Z. Morris, Fortune, "The Apple Card’s Algorithm Goes Both Ways on Women’s Credit Limits," 13 Nov. 2019 Hygiea was initially thought to be a large asteroid, but new analysis of observations made by Chile’s Very Large Telescope revealed insight into the celestial body. Jennifer Leman, Popular Mechanics, "Our Solar System’s Could Soon Gain Another Dwarf Planet," 28 Oct. 2019 Braun will also superintend work on an ambitious orbital mission to the Jupiter system focused on its icy moon Europa as well as the Psyche mission to a metallic asteroid. Eric Berger, Ars Technica, "NASA signals openness to change with new Solar System exploration hire," 30 Sep. 2019 Putting off to tomorrow Dislocation on such a scale might be undertaken if a large asteroid on a fixed trajectory were set to devastate North America on January 1st 2031. The Economist, "The past, present and future of climate change," 21 Sep. 2019 The young girls, ranging from kindergartners to eighth graders, learned about the solar system, asteroids and constellations. Brooke Lamantia,, "Dreams of space travel take flight at Girl Scout camp," 25 July 2019 Recent Examples on the Web: Adjective The other asteroid movie, Armageddon, famously came out two months after Deep Impact. Michael O'connell, The Hollywood Reporter, "'Morning Show' Director Mimi Leder on How to Film Jennifer Aniston," 31 Oct. 2019 Manny, Sid, Diego and the rest of the herd must leave home after Scrat’s adventure in outer space sends an asteroid hurtling toward Earth. Los Angeles Times, "Movies on TV for Oct. 6-12: ‘Throne of Blood’ and more," 4 Oct. 2019 While the narrator fixes his plane, the Prince tells him his story, which begins on his home planet, asteroid B-612, which is about the size of a house. Jason Daley, Smithsonian, "Early Sketches From ‘The Little Prince’ Found in Swiss Collection," 20 Aug. 2019 Unlike the first attempt, this time, the team was aiming to nab material from the asteroid’s interior, which hasn’t been subjected to as much radiation as its surface. Mary Beth Griggs, The Verge, "Watch a Japanese spacecraft grab another sample from an asteroid," 27 July 2019 The first thing to look at is actually what was happening before the asteroid impact. Scott K. Johnson, Ars Technica, "End-Cretaceous mass extinction saw big swings in ocean pH," 24 Oct. 2019 Scientists have known little about the mammals that survived and flourished in the years after the asteroid impact. Doyle Rice, USA TODAY, "Rise of the mammals: Trove of 66-million-year-old fossils discovered from post-dinosaur era," 24 Oct. 2019 Considering how widespread and catastrophic the damage was across Earth after the asteroid impact, 700,000 years doesn't seem that long. Ashley Strickland, CNN, "New fossil treasure trove shows what happened for a million years after the dinosaurs went extinct," 24 Oct. 2019 The data from White Pond are, however, consistent with the growing body of evidence that a comet or asteroid collision caused continent-scale environmental calamity 12,800 years ago, via vast burning and a brief impact winter. Christopher R. Moore, The Conversation, "New evidence that an extraterrestrial collision 12,800 years ago triggered an abrupt climate change for Earth," 22 Oct. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'asteroid.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of asteroid


1802, in the meaning defined at sense 1


1824, in the meaning defined at sense 1

History and Etymology for asteroid


Greek asteroeidēs starlike, from aster-, astēr

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Time Traveler for asteroid

Time Traveler

The first known use of asteroid was in 1802

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Statistics for asteroid

Last Updated

9 Dec 2019

Cite this Entry

“Asteroid.” The Dictionary, Merriam-Webster Inc., Accessed 9 December 2019.

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More Definitions for asteroid


How to pronounce asteroid (audio)

English Language Learners Definition of asteroid

: any one of thousands of small planets that circle around the sun


as·​ter·​oid | \ ˈa-stə-ˌrȯid How to pronounce asteroid (audio) \

Kids Definition of asteroid

: one of thousands of rocky objects that move in orbits mostly between those of Mars and Jupiter and have diameters from a fraction of a mile to nearly 500 miles (800 kilometers)


as·​ter·​oid | \ ˈas-tə-ˌrȯid How to pronounce asteroid (audio) \

Medical Definition of asteroid

: resembling a star

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More from Merriam-Webster on asteroid

Rhyming Dictionary: Words that rhyme with asteroid

Spanish Central: Translation of asteroid

Nglish: Translation of asteroid for Spanish Speakers

Britannica English: Translation of asteroid for Arabic Speakers Encyclopedia article about asteroid

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