a. Astronomy A band of the celestial sphere extending about 8° to either side of the ecliptic that represents the path of the principal planets, the moon, and the sun.
b. In astrology, this band divided into 12 equal parts called signs, each 30° wide, bearing the name of a constellation for which it was originally named but with which it no longer coincides owing to the precession of the equinoxes.
c. A diagram or figure representing the zodiac.
2. A complete circuit; a circle.
[Middle English, from Old French zodiaque, from Latin zōdiacus, from Greek zōidiakos (kuklos), (circle) of the zodiac, from zōidion, small represented figure, zodiacal sign, diminutive of zōion, living being; see ZOON.]
zo·dia·cal (-dīə-kəl) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.