- (astronomy) Any of the 8 celestial bodies which orbit the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune (a celestial body that fits the 2006 IAU definition of planet).
- (astronomy) Any planet that is significantly larger and more massive than Earth, containing large amounts of hydrogen and helium, such as Jupiter and Neptune.
- (larger than Earth): minor planet (smaller than Earth (in the Solar System))
- (2006 IAU definition of planet): dwarf planet (a planet that does not fit the 2006 IAU definition of planet (i.e. Pluto))