Zodiac denotes an annual cycle of twelve stations along the ecliptic, the apparent path of the Sun across the heavens through the constellations that divide the ecliptic into twelve equal zones of celestial longitude. The zodiac is recognized as the first known celestial coordinate system. Babylonian astronomers developed the zodiac of twelve signs. The term zodiac comes from the Latinzōdiacus, from the Greek ζῳδιακός [κύκλος] (zodiakos kyklos), meaning “circle of animals”, derived from ζῴδιον (zodion), the diminutive of ζῷον (zoon) “animal”. The American Heritage Dictionary(1970) derives the word further from Indo-European ‘gwei-‘, ‘to live’. ‘zoe’, ‘life’ is listed as the suffixed form of this Indo-European word. However, the classical Greek zodiac also includes signs (also constellations) that are not represented by animals (e.g., Aquarius, Virgo, Gemini, and—for some—Libra). Another suggested etymology is that the Greek term is cognate with the Sanskrit sodi, denoting “a path”, i.e., the path through which the Sun travels. 
The zodiac also means a region of the celestial sphere that includes a band of eight arc degrees above and below the ecliptic, and therefore encompasses the paths of the Moon and the naked eye planets (Mercury, Venus, Mars, Jupiter, and Saturn). The classical astronomers called these planets wandering stars to differentiate them from the fixed stars of the celestial sphere (Ptolemy). Astrologers understood the movement of the planets and the Sun through the zodiac as a means of explaining and predicting events on Earth.