WordNet (r) 3.0 (2006):

major 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]