cometyoudaoicibaDictYouDict
comet: [13] Comet means literally ‘the longhaired one’. Greek kómē meant ‘hair’, but it was also applied metaphorically to the tail of a comet, which was thought of as streaming out behind like a luxuriant head of hair being blown by the wind. Hence an astēr kométēs ‘longhaired star’ was the name given to a comet. Eventually the adjective kométēs came to stand for the whole phrase, and it passed via Latin comēta and Old French comete into English.
comet (n.)youdaoicibaDictYouDict
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" (compare koman "let the hair grow long"), which is of unknown origin. So called from resemblance of a comet's tail to streaming hair.