Definition of primary planet in US English:

primary planet


  • A planet that directly orbits the sun.

    • ‘Pluto also has a relatively large moon (1,400km across) named Charon, which is regarded as the largest moon in the Solar System with respect to the size of its primary planet.’
    • ‘The primary planets comprise the major planets, of which nine are known, viz., in order of distance from the Sun, Mercury, Venus, the Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto, and the minor planets or asteroids, the orbits of which lie between those of Mars and Jupiter.’
    • ‘Valon was the primary planet in the Tiroc system.’