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

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 Across the universe Walking on Bennu, a near-Earth asteroid, would be a bit like wading through a ball pit, NASA scientists have found. Katie Hunt, CNN, 6 Aug. 2022 This one calls for launching a pair of spacecraft to a binary asteroid, completing two Earth flybys on the way. Wired, 29 July 2022 Lindy Elkins-Tanton is the principal investigator for a NASA probe slotted to fly out to the asteroid belt to study a rare, metal-rich asteroid called Psyche. Marcia Bartusiak, Washington Post, 29 July 2022 Despite not being hazardous, NF 2022 was still a bus-sized asteroid. Joshua Hawkins, BGR, 7 July 2022 But in a press conference on Friday, NASA announced that the $985 million Psyche mission —- the agency’s first mission designed to study a metal-rich asteroid —- would not launch this year. Bruce Dorminey, Forbes, 25 June 2022 The Hayabusa2 spacecraft arrived at Ryugu, a carbon-rich asteroid, in 2018. New York Times, 9 June 2022 And a gigantic asteroid will whizz by Earth this week. Laura L. Davis, USA TODAY, 23 May 2022 The asteroid is the focus of NASA's Psyche mission, launching later this year. Jennifer Ouellette, Ars Technica, 16 June 2022 Recent Examples on the Web: Adjective And token owners will have the right to purchase the ore, and other resources, like water, from the asteroid mining activities. Eric Berger, Ars Technica, 22 July 2022 To fill out Black Beauty’s history, the team first studied both the rock itself and asteroid events on Mars. Tim Newcomb, Popular Mechanics, 20 July 2022 Back in 2020, NASA sent a small spacecraft known as OSIRIS-REx to collect samples from the asteroid Bennu. Joshua Hawkins, BGR, 8 July 2022 Problematically, Psyche's launch included a ride-along for a separate asteroid mission called Janus that has its own launch windows, so the review will need to include NASA's entire Discovery Mission program more broadly. John Timmer, Ars Technica, 24 June 2022 That's 20 million years before an asteroid impact wiped out three quarters of life on Earth. Scott Gleeson, USA TODAY, 24 May 2022 Some nations, like China, have proposed plans for asteroid detection systems. Joshua Hawkins, BGR, 7 July 2022 The asteroid Psyche is an unusual body in the Solar System. John Timmer, Ars Technica, 24 June 2022 The paper, published in the Proceedings of the Japan Academy, is among the first analyses of the asteroid dust and pebbles that were carried by the Japanese space probe Hayabusa2 and dropped off in the Australian outback in December 2020. Peter Landers, WSJ, 10 June 2022 See More

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.

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

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The first known use of asteroid was in 1802

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Dictionary Entries Near asteroid



asteroid belt

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Statistics for asteroid

Last Updated

13 Aug 2022

Cite this Entry

“Asteroid.” Dictionary, Merriam-Webster, Accessed 15 Aug. 2022.

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More Definitions for asteroid


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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