major planet

Wiktionary

1. n. Any of the 8 celestial bodies which orbit the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
2. n. Any planet that is significantly larger and more massive than Earth, containing large amounts of hydrogen and helium, such as Jupiter and Neptune.http://www.seasky.org/astronomy/astronomy_glossary.html
3. n. Those planets that are larger than the Earth; specifically Jupiter , Saturn , Uranus , Neptune (in the Solar System)
4. n. a celestial body that fits the 2006 IAU definition of planet

WordNet 3.0

1. n. (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