noun

1. Obsolete any of the celestial objects with apparent motion (as distinguished from the apparently still stars), including the sun, moon, Mercury, Venus, Mars, Jupiter, or Saturn
2. now, a large, opaque, nonluminous mass, usually with its own moons, that revolves about a star; esp., one of the sun's nine major planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto
3. Astrol. any celestial body thought of as influencing human lives

Etymology: ME planete < OFr < LL planeta < Gr planētēs, wanderer < planan, to lead astray, wander < IE base *plā-, flat, spread out > plain