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[kom-it] /ˈkɒm ɪt/
noun, Astronomy.
a celestial body moving about the sun, usually in a highly eccentric orbit, consisting of a central mass surrounded by an envelope of dust and gas that may form a tail that streams away from the sun.
Origin of comet
1150-1200; Middle English comete < Anglo-French, Old French < Latin comētēs, comēta < Greek komḗtēs wearing long hair, equivalent to komē-, variant stem of komân to let one's hair grow (derivative of kómē hair) + -tēs agent suffix
Related forms
[kom-i-ter-ee] /ˈkɒm ɪˌtɛr i/ (Show IPA),
[kuh-met-ik] /kəˈmɛt ɪk/ (Show IPA),
cometical, adjective
cometlike, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for cometary
Historical Examples
  • Was the division of the cometary mass produced by the encounter?

    Meteoric astronomy: Daniel Kirkwood
  • Subsequently sodium and iron lines were found in cometary spectra.

    Curiosities of the Sky Garrett Serviss
  • That numerous facts—some observed in ancient and some in modern times—have been decidedly indicative of cometary disintegration.

    Comets and Meteors Daniel Kirkwood
  • Before entering the solar domain, they were doubtless members of a cometary system.

    Comets and Meteors Daniel Kirkwood
  • At one of these epochs the cometary orbit will probably undergo considerable transformation.

    Comets and Meteors Daniel Kirkwood
  • On the third, however, the cometary fragment was found, and its motion accurately measured.

    Comets and Meteors Daniel Kirkwood
  • That all meteors were originally parts of cometary masses is however a theory that may be accepted without much hesitation.

    Astronomy David Todd
  • The second type tails are somewhat curved, or plume-like, and they form the most common type of cometary tail.

    Astronomy David Todd
  • With no pilot, the ship would go into a cometary orbit around the sun.

    Last Resort Stephen Bartholomew
  • The Astronomical portion, by Mr. Barker, is unusually copious, and the cometary plates are well executed.

British Dictionary definitions for cometary


a celestial body that travels around the sun, usually in a highly elliptical orbit: thought to consist of a solid frozen nucleus part of which vaporizes on approaching the sun to form a gaseous luminous coma and a long luminous tail
Derived Forms
cometary, cometic (kɒˈmɛtɪk) adjective
Word Origin
C13: from Old French comète, from Latin comēta, from Greek komētēs long-haired, from komē hair
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for cometary



c.1200, from Old French comete (12c., Modern French comète), from Latin cometa, from Greek (aster) kometes, literally "long-haired (star)," from kome "hair of the head" (cf. koman "let the hair grow long"), of unknown origin. So called from resemblance of a comet's tail to streaming hair.

Online Etymology Dictionary, © 2010 Douglas Harper
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cometary in Science
A celestial object that orbits the Sun along an elongated path. A comet that is not near the Sun consists only of a nucleus—a solid core of frozen water, frozen gases, and dust. When a comet comes close to the Sun, its nucleus heats up and releases a gaseous coma that surrounds the nucleus. A comet forms a tail when solar heat or wind forces dust or gas off its coma, with the tail always streaming away from the Sun. ◇ Short-period comets have orbital periods of less than 200 years and come from the region known as the Kuiper belt. Long-period comets have periods greater than 200 years and come from the Oort cloud. See more at Kuiper belt, Oort cloud. See Note at solar system.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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cometary in Culture

comet definition

An object that enters the inner solar system, typically in a very elongated orbit around the sun. Material is boiled off from the comet by the heat of the sun, so that a characteristic tail is formed. The path of a comet can be in the form of an ellipse or a hyperbola. If it follows a hyperbolic path, it enters the solar system once and then leaves forever. If its path is an ellipse, it stays in orbit around the sun.

Note: Comets were once believed to be omens, and their appearances in the sky were greatly feared or welcomed.
Note: The most famous comet, Comet Halley (or Halley's comet), passes close to the Earth roughly every seventy-six years, most recently in 1986.
The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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