A member of the solar system which usually moves in an elongated orbit, approaching very near to the sun in its perihelion, and receding to a very great distance from it at its aphelion. A comet commonly consists of three parts: the nucleus, the envelope, or coma, and the tail; but one or more of these parts is frequently wanting. See Illustration in Appendix.
A bright star-like heavenly body, composed of masses of tiny particles and gases, which follows an eccentric orbit of the Sun that for some comets can take thousands of years to complete. Most comets form luminous "tails", bits of meteroic material and gases that stream off into space, when they near the Sun.
a piece of ice wandering through space commonly called a "dirty snowball"