plan·​et·​oid ˈpla-nə-ˌtȯid How to pronounce planetoid (audio)
: a small body resembling a planet
especially : asteroid
planetoidal adjective

Examples of planetoid in a Sentence

Recent Examples on the Web Earth formed right along with everything else as particles joined to form clumps and then boulders and planetoids. Matt Hrodey, Discover Magazine, 24 Oct. 2023 When Ripley crash-lands on the planetoid along with one xenomorph running loose and a another one growing inside her, the monks regard her as a kind of witch. Chris Klimek, Smithsonian Magazine, 27 Mar. 2023 Ward imagined a sort of space monastery populated by an all-male religious order that used futuristic technology only insofar as necessary to sustain life support on their artificial planetoid, which was patterned on 10th-century Earth, complete with artificial lakes and wheatfields. Chris Klimek, Smithsonian Magazine, 27 Mar. 2023 There is evidence that infant Earth was struck by a large planetoid called Theia. Eric Betz, Discover Magazine, 9 May 2021 That said, 2001 FO32's path will present astronomers with a rare opportunity to closely observe the planetoid because 1.25 million miles is still relatively close in astronomical terms. Julia Musto, Fox News, 13 Mar. 2021 Samples were first found in a meteorite (believed to be remains of a fragmented planetoid) that fell from space in 1879, but only in 2014 described as a distinct mineral. David Bressan, Forbes, 4 Mar. 2021 Ian Sample at The Guardian reports that the researchers didn’t press their eye to the telescope lens to find the little planetoids. Jason Daley, Smithsonian, 9 Oct. 2019 Without a star to call their own, the planetoids cool to a temperature that makes finding them a task for infrared eyes. National Geographic, 5 Jan. 2017 See More

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

Word History

First Known Use

1803, in the meaning defined above

Time Traveler
The first known use of planetoid was in 1803

Dictionary Entries Near planetoid

Cite this Entry

“Planetoid.” Dictionary, Merriam-Webster, Accessed 7 Dec. 2023.

Kids Definition


: a body resembling a planet

More from Merriam-Webster on planetoid

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