Merriam Webster defines the Zodiac as:
”An imaginary band in the heavens centered on the ecliptic that encompasses the apparent paths of all the planets and is divided into 12 constellations or signs each taken for astrological purposes to extend 30 degrees of longitude.”

For purposes of Astrology, we first consider:
“The zodiac is where we find the exact location of planets and other celestial phenomena, as they move through the sky, viewed from our vantage point on Earth.”