The Greeks built their calendar from the twelve principal constellations as they took their turns in the sky overhead, but the calendar was represented graphically by a circle in which figures representing the constellations were entered. This representation was called zodiakos kyklos, or the circle of the figures. The phrase originated from zodian - a figurine, usually of an animal - and kyklos, a circle. The phrase became abbreviated to zodiakos, which was taken into Latin as zodiacus and then into English with the spelling change.
This was originally the name of a snake god in the voodoo cult of West Africa, and later of the Caribbean. It comes from a West African language called Kongo, and is related to the words "nzambi" (god) and "zumbi" (fetish). It was later applied to a reanimated corpse in voodoo.
The Greek word zōion meant animal. From it was formed the modern Latin zōologia, or study of animals, which was adapted into English as zoology. Zoological was derived from this in the 19th century, and when the Zoological Society of London opened their exhibition of live wild animals in Regent's Park in 1829, they called it the Zoological Gardens. This was soon abbreviated to "the Zoological," and by the mid 1840s it had shrunk further to just "zoo."
