From AMS Glossary
(Also called zodiacal band.) The position of the sun during the course of a year as it appears to move through successive star groups or constellations; that is, the band of the celestial sphere, 16° in width, through which the ecliptic runs centrally.
At all times this band of the heavens contains the sun, the moon, and the principal planets except Venus and Pluto. Ancient astrologers divided the zodiac into twelve equal divisions, each 30° long, and named them for the chief constellations found in each division, the twelve constellations of the zodiac. These constellations were thought by the ancient Greeks (and others) to represent characters in their mythology and were identified with them.