com·​et ˈkä-mət How to pronounce comet (audio)
: a celestial body that appears as a fuzzy head usually surrounding a bright nucleus, that has a usually highly eccentric orbit, that consists primarily of ice and dust, and that often develops one or more long tails when near the sun
cometary adjective
cometic adjective

Example Sentences

Recent Examples on the Web The rings surrounding one of the brightest stars in the universe are made of debris, gas, and dust that come from the fallout of collisions of bodies like asteroids and comets. Eden Villalovas, Washington Examiner, 8 May 2023 Aside from the occasional asteroid or comet impact, most larger objects stick to their orbital lanes. Robin George Andrews, New York Times, 8 May 2023 Near-Earth objects are asteroids and comets that orbit the sun like the planets. Nadine El-bawab, ABC News, 3 May 2023 Every year, the Earth passes near the path of the comet. Julia Musto, Fox News, 22 July 2022 In mid-April of each year, Earth runs into the stream of debris from the comet, causing the meteor shower. Doyle Rice, USA TODAY, 15 Apr. 2022 Both worlds may have migrated early in their lives, which would have shifted their positions around the sun and sent barrages of water-rich comets cascading toward Earth and other inner planets. Shannon Hall, Scientific American, 30 Mar. 2023 The comet should be visible through binoculars in the morning sky for sky watchers in the Northern Hemisphere during most of January and those in the Southern Hemisphere in early February, according to NASA. Ashley Strickland, CNN, 30 Dec. 2022 The shower will peak Oct. 21-2 and continue through early November as the Earth completes it annual trip through the tail of Halley’s comet. Leada Gore |, al, 11 Oct. 2022 See More

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

Word History


Middle English comete, from Old English cometa, from Latin, from Greek komētēs, literally, long-haired, from koman to wear long hair, from komē hair

First Known Use

before the 12th century, in the meaning defined above

Time Traveler
The first known use of comet was before the 12th century

Dictionary Entries Near comet

Cite this Entry

“Comet.” Dictionary, Merriam-Webster, Accessed 31 May. 2023.

Kids Definition


com·​et ˈkäm-ət How to pronounce comet (audio)
: a bright heavenly body that develops a cloudy tail as it moves closer to the sun in its orbit

Old English cometa "comet," from Latin cometa (same meaning), from Greek komētēs, literally, "long-haired," derived from komē "hair" — related to coma entry 2

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