belonging to times long past especially of the historical period before the fall of the Western Roman Empire; "ancient history"; "ancient civilizations such as those of the Etruscans and Sumerians"; "ancient Greece"
(astronomy) any of the nine large celestial bodies in the solar system that revolve around the sun and shine by reflected light; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto in order of their proximity to the sun; viewed from the constellation Hercules, all the planets rotate around the sun in a counterclockwise direction
any celestial body (other than comets or satellites) that revolves around a star
any imaginary place where spiritual beings (demons or fairies or angels or the like) abide; "science has emptied the spirit world of its former inhabitants"