zodiac

n. 1 belt of the heavens including all apparent positions of the sun, moon, and planets as known to ancient astronomers, and divided into twelve equal parts (signs of the zodiac). 2 diagram of these signs.  zodiacal adj. [greek zoion animal]

n. An imaginary belt in the heavens, 16 or 18 broad, in the middle of which is the ecliptic, or sun's path. It comprises the twelve constellations, which one constituted, and from which were named, the twelve signs of the zodiac.