comet (n.) Look up comet at Dictionary.com
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.