comet

noun

com·​et ˈkä-mət 

: 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

ˈkä-mə-ˌter-ē 

adjective

cometic

kə-ˈme-tik 

kä-

adjective

Examples of comet in a Sentence

Recent Examples on the Web

Astronomers have detected simple organic molecules drifting through interstellar clouds and preserved in meteorites and comets, indicating that biologically important compounds can form in space and be delivered to planetary surfaces. —Victoria Corless, Space.com, 28 Jan. 2026

Future space missions that sample comets, asteroids, or even interstellar dust may be able to test this idea directly by looking not just for individual amino acids but also for short peptides like those produced in these experiments. —William A. Haseltine, Forbes.com, 28 Jan. 2026

Some of the solar system’s most distant comets can be very confusing. —Andrew Paul, Popular Science, 22 Jan. 2026

Where the two meet, bundles of the hotter stuff pierce the dusty shell, creating knotty plumes that look vaguely like comets. —Joseph Howlett, Scientific American, 20 Jan. 2026

Word History

Etymology

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

Rhymes for comet

• grommet
• vomit
• recommit

Kids Definition

comet

noun

com·​et ˈkäm-ət 

: a bright heavenly body that develops a cloudy tail as it moves closer to the sun in its orbit

Etymology

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