Search Result for "outer planet":
Wordnet 3.0

NOUN (1)

1. (astronomy) a major planet whose orbit is outside the asteroid belt (Jupiter, Saturn, Uranus, Neptune, Pluto); 



WordNet (r) 3.0 (2006):

outer planet
    n 1: (astronomy) a major planet whose orbit is outside the
         asteroid belt (Jupiter, Saturn, Uranus, Neptune, Pluto)