Pronunciation: (zō'dē-ak"), [key]
1. an imaginary belt of the heavens, extending about 8° on each side of the ecliptic, within which are the apparent paths of the sun, moon, and principal planets. It contains twelve constellations and hence twelve divisions called signs of the zodiac. Each division, however, because of the precession of the equinoxes, now contains the constellation west of the one from which it took its name. Cf. sign of the zodiac.
2. a circular or elliptical diagram representing this belt, and usually containing pictures of the animals, human figures, etc., that are associated with the constellations and signs.
3. a circuit or round.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.