n. One of a class of celestial bodies which move about the sun in greatly elongated orbits, usually elliptical or parabolic.n. In heraldry, same as blazing-star.n. One of a group of humming-birds with long forked tails: as, the Sappho comet, Cometes sappho; the Phaon comet, Cometes phaon.n. A game of cards, somewhat like speculation, invented and popular in the reign of Louis XV. of France.n. n. In photography, a comet-shaped defect appearing on gelatin dry plates.