ALL meanings of outer planet
out·er plan·et
O o - noun outer planet any of the four planets with orbits outside the orbit of Mars, namely, the planets Jupiter, Saturn, Uranus, and Neptune. 1
- noun outer planet any of the planets Jupiter, Saturn, Uranus, Neptune, and (formerly) Pluto, whose orbit lies outside the asteroid belt 0
- noun outer planet any of the five planets with an orbit outside of the orbit of Mars; Jupiter, Saturn, Uranus, Neptune, or Pluto 0