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

Keep scrolling for more

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 The largest asteroid, named 2014 SD224, has a diameter of 689 feet. Jennifer Leman, Popular Mechanics, "A Potentially Hazardous Asteroid Is Flying Past Earth on Christmas Day," 24 Dec. 2020 Hayabusa2, meanwhile, is on an 11-year expedition to another small and distant asteroid, 1998KY26, to try to study possible defenses against meteorites that could fly toward Earth. Mari Yamaguchi,, "Japanese spacecraft’s gifts: Asteroid chips like charcoal," 24 Dec. 2020 The Geminid shower is unusual, possibly unique, in that its source is a rather pipsqueak-ish asteroid, 3200 Phaeton, rather than a disintegrating comet. al, "Geminid meteor shower 2020: Where to watch," 13 Dec. 2020 On board were pieces of an asteroid, the biggest such haul in history, captured millions of kilometers from Earth and returned safely to our planet. Jonathan O'callaghan, Scientific American, "Asteroid Dust from Hayabusa2 Could Solve a Mystery of Planet Creation," 8 Dec. 2020 Geminid meteors Most meteor showers originate from comets, but the Geminid meteor shower actually originates from the aforementioned asteroid, 3200 Phaethon. Chris Ciaccia, Fox News, "Geminid meteor shower is coming: what to know," 8 Dec. 2020 Japan has once again retrieved samples from a distant asteroid, which scientists will scrutinize for clues about the ancient delivery of water and organic molecules to Earth. Dennis Normile, Science | AAAS, "Japan’s Hayabusa2 capsule lands with carbon-rich asteroid samples," 7 Dec. 2020 It’s either a near-Earth asteroid or an extinct comet, sometimes called a rock comet, according to NASA. Doyle Rice, USA TODAY, "Head's up! Here comes the Geminid meteor shower!," 6 Dec. 2020 Ever wondered what an asteroid’s surface, a clownfish embryo, or the microbes within a kiss look like up close? Michael Greshko, Science, "The best science pictures of 2020," 4 Dec. 2020 Recent Examples on the Web: Adjective Japanese space agency officials were delighted Tuesday by the return of a small capsule containing asteroid soil samples obtained by their Hayabusa2 spacecraft and were anxiously waiting to look inside after preparations are complete. Mari Yamaguchi, USA TODAY, "Asteroid samples arrive in Japan for research: Hayabusa2 capsule returns after 6-year 'space journey'," 9 Dec. 2020 The follow-up mission—aptly named Hayabusa2—launched from Tanegashima Space Center in Tanegashima, Japan on December 3, 2014, kicking off an almost four-year journey to the asteroid Ryugu. Jennifer Leman, Popular Mechanics, "Watch This Spacecraft Drop a Piece of an Asteroid in the Australian Outback," 4 Dec. 2020 The missions will also study the history of asteroid impacts on the Earth and moon, and search for compounds buried beneath the surface, including water ice. Science, "One of these astronauts may be the first woman on the moon," 9 Dec. 2020 There an instrument extracted gases within the capsule that may have been released by the asteroid rocks as they were shaken and broken during re-entry. New York Times, "Japan’s Journey to an Asteroid Ends With a Hunt in Australia’s Outback," 5 Dec. 2020 The agency is awaiting the return of precious cargo—a roughly 10-gram sample of the asteroid Ryugu—collected two years ago by its Hayabusa2 spacecraft. Jennifer Leman, Popular Mechanics, "Watch This Spacecraft Drop a Piece of an Asteroid in the Australian Outback," 4 Dec. 2020 More recently, the TV show The Expanse depicts the lives of asteroid miners as an outright form of slavery. Clive Thompson, The New Republic, "Monetizing the Final Frontier," 3 Dec. 2020 For the second time ever, humanity has brought asteroid samples down to Earth. Mike Wall, Scientific American, "Japanese Space Capsule Carrying Pristine Asteroid Samples Lands in Australia," 7 Dec. 2020 In its first touchdown in February 2019, the spacecraft collected surface dust samples, similar to NASA’s recent touch-and-go grab by Osiris REx on the asteroid Bennu. Mari Yamaguchi, The Christian Science Monitor, "Asteroid samples: Japanese space capsule brings ‘treasure box’ to Earth," 7 Dec. 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.

See More

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

Keep scrolling for more

Learn More about asteroid

Time Traveler for asteroid

Time Traveler

The first known use of asteroid was in 1802

See more words from the same year

Statistics for asteroid

Last Updated

9 Jan 2021

Cite this Entry

“Asteroid.” Dictionary, Merriam-Webster, Accessed 17 Jan. 2021.

Keep scrolling for more

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

Keep scrolling for more

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

Comments on asteroid

What made you want to look up asteroid? Please tell us where you read or heard it (including the quote, if possible).


Test Your Vocabulary

Words of Snow and Ice Quiz

  • image1037863653
  • Which of the following refers to thin, bending ice, or to the act of running over such ice?
True or False

Test your knowledge - and maybe learn something along the way.


Anagram puzzles meet word search.

Love words? Need even more definitions?

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