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
2 : starfish



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 asteroid (audio) \ adjective

Examples of asteroid in a Sentence

Noun Most asteroids are found between Mars and Jupiter.
Recent Examples on the Web: Noun Psyche mission to an asteroid, slated to launch next year, will follow. Joshua Sokol, Science | AAAS, "Nature’s most magnetic objects, ripped apart in starquakes, can unleash powerful flashes of light," 8 Apr. 2021 An asteroid entered Earth's atmosphere over Chelyabinsk, Russia, in 2013. Katie Hunt, CNN, "A meteorite exploded in the air above Antarctica 430,000 years ago," 31 Mar. 2021 Other astronomical features that Butler has been named after include a mountain on Pluto’s moon Charon and an asteroid, SYFY Wire reports. Elizabeth Gamillo, Smithsonian Magazine, "Perseverance Rover Landing Site Named After Science Fiction Author Octavia E. Butler," 12 Mar. 2021 My 3-year-old was convinced that the sun had turned into an asteroid. New York Times, "7 Questions 75 Artists 1 Very Bad Year," 10 Mar. 2021 If an asteroid or meteoroid does not burn up before impact, it is called a meteorite. Julia Musto, Fox News, "Fireball seen over New England, Canada explodes with force of 440 lbs of TNT," 9 Mar. 2021 Under Barack Obama, reaching an asteroid and Mars were the goals. Washington Post, "The Biden administration has set out to dismantle Trump’s legacy except in one area: space," 2 Mar. 2021 There is growing consensus that intelligent life here may well have depended on improbable contingencies such as the Chicxulub asteroid impact, sixty-six million years ago, which obliterated the dinosaurs. The New Yorker, "The Mail," 8 Feb. 2021 Various ices are fine; large amounts of hydrogen and helium can easily survive when bound to a gas giant; asteroid-like and comet-like bodies are common. Ethan Siegel, Forbes, "Ask Ethan: Were Mars And Venus Ever Living Planets?," 16 Apr. 2021 Recent Examples on the Web: Adjective New images captured by the spacecraft after a close flyby of the asteroid April 7 show the aftermath following the brief touchdown of OSIRIS-REx, which had collected 2 ounces of rocky material. Ashley Strickland, CNN, "This is what an asteroid looks like after playing tag with a spacecraft," 20 Apr. 2021 Some researchers think the asteroid impact might have dramatically increased the availability of nutrients in the soil, perhaps by raining down particulate and through the ashes of incinerated life. Alex Fox, Smithsonian Magazine, "How the Dinosaur-Killing Asteroid Spurred the Evolution of the Modern Rainforest," 1 Apr. 2021 This suggests that volcanism wasn’t what triggered the extinction and supports the theory that the asteroid impact was a more likely cause. Mike Wehner, BGR, "Did volcanoes make the dinosaur extinction even worse?," 30 Mar. 2021 After sifting through the data, the paleontologists didn’t find any sign that dinosaurs were declining before the asteroid strike. Riley Black, Smithsonian Magazine, "The Top Ten Dinosaur Discoveries of 2020," 23 Dec. 2020 In addition to iridium, the crater section showed elevated levels of other elements associated with asteroid material. David Bressan, Forbes, "Scientists Find Traces Of Asteroid That Wiped Out The Dinosaurs," 24 Feb. 2021 After a journey of more than 3.2 billion miles, Hayabusa 2 flew by Earth this weekend and released a capsule that Japanese officials hope will contain at least 0.1 gram of asteroid material, the equivalent of a few grains of rice. Peter Landers, WSJ, "Japan’s Asteroid Odyssey: 3 Billion Miles for a Pinch of Dust," 6 Dec. 2020 After a series of high-stakes maneuvers performed more than 200 million miles from Earth, NASA’s OSIRIS-REx spacecraft has successfully stowed its precious samples of the asteroid Bennu. National Geographic, "NASA's OSIRIS-REx secures asteroid sample after surprise leak," 29 Oct. 2020 Following Tuesday's historic touchdown on the asteroid Bennu, NASA has released never-before-seen images of the OSIRIS-REx spacecraft kicking up rocks and debris on the space rock's surface. Chris Ciaccia, Fox News, "NASA releases never-before-seen pictures of Bennu, an asteroid that may hold the building blocks of life," 22 Oct. 2020

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 May 2021

Cite this Entry

“Asteroid.” Dictionary, Merriam-Webster, Accessed 14 May. 2021.

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More Definitions for asteroid



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

More from Merriam-Webster on asteroid

Nglish: Translation of asteroid for Spanish Speakers

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

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