planet.

1. Noun

   (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

2. Noun

   a person who follows or serves another

3. Noun

   any celestial body (other than comets or satellites) that revolves around a star

Open English WordNet · CC BY 4.0. Attribution and changes.

1. Nounhistorical

   Each of the seven major bodies which move relative to the fixed stars in the night sky—the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn.

2. Nounhistorical

   Any body that orbits the Sun, including the asteroids (as minor planets) and sometimes the moons of those bodies (as satellite planets)

3. Noun

   A body which is massive enough to be in hydrostatic equilibrium (generally resulting in being an ellipsoid) but not enough to attain nuclear fusion and, in IAU usage, which directly orbits a star (or multiple star) and dominates the region of its orbit; specifically, in the case of the Solar system, the eight major bodies of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

4. Noun

   construed with the or this: The Earth.

Wiktionary contributors · CC BY-SA 4.0. Attribution and changes.