Meaning

noun (astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit

originFrom Middle English comete, partly from Old English comēta and partly from Old French comete, both from Latin comētēs, from Ancient Greek κομήτης (komḗtēs, “longhaired”), short for ἀστὴρ κομήτης ([astēr] komētēs, "longhaired [star])" and referring to the tail of a comet, from κόμη (kómē, “hair”). Compare English faxed star and Latin crīnīta stēlla (“comet”, literally “(long) haired star”).

Etymology from Wiktionary, CC BY-SA 3.0