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noun com·et \ˈkä-mət\

: an object in outer space that develops a long, bright tail when it passes near the sun

Full Definition of COMET

:  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
com·e·tary \-mə-ˌter-ē\ adjective
co·met·ic \kə-ˈme-tik, kä-\ adjective

Origin of COMET

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 12th century

Other Astronomy Terms

gibbous, nadir, nebulous, penumbra, retrograde, sidereal, syzygy, wane, wax, zenith
COMET Defined for Kids


noun com·et \ˈkä-mət\

Definition of COMET for Kids

:  a small bright heavenly body that develops a cloudy tail as it moves in an orbit around the sun

Word History of COMET

The tail of a comet looks rather like long hair streaming behind the head. The ancient Greeks named comets with the word komētēs, which means literally long-haired. This word comes from the noun komē, hair on one's head or shock of hair. The English word comet came from the Greek name for comets.


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