Definitions
1.NounAny secondary body in the Solar system that is geologically differentiated or in hydrostatic equilibrium and thus has a planet-like geology: a planet, dwarf planet, or the larger moons and asteroids.
2.NounAny substantial body in orbit around the Sun or other star: a planet, minor planet, or comet.
3.NounAny substantial body associated with the development of planets: a protoplanet, planetesimal.