From WordNet (r) 3.0 (2006):
planet
n 1: (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 [syn: planet, major planet]
2: a person who follows or serves another [syn: satellite,
planet]
3: any celestial body (other than comets or satellites) that
revolves around a star