| any of the five planets with orbits outside the orbit of Mars: Jupiter, Saturn, Uranus, Neptune, and Pluto. |
| outer planet n. Any of the four planets, Jupiter, Saturn, Uranus, and Neptune, with orbits outside that of Mars. |
| outer planet
Any of the five planets Jupiter, Saturn, Uranus, Neptune, and Pluto, whose orbits lie outside that of Mars. With the exception of Pluto, the outer planets are large gas giants. Compare inner planet. See also superior planet. |
