planet -
(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
planet -
A large body which directly orbits any star or star cluster but which has not attained nuclear fusion.
planet -
In phrases such as the planet, this planet, sometimes refers to the Earth.
Wikipedia
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals. The term planet is ancient, with ties to history, science, mythology, and religion. The planets were originally seen by many early cultures as divine, or as emissaries of the gods.
OmegaWiki Dictionary
Ω
planet A large, heavy body, which does not produce energy by nuclear fusion, moving in a stable elliptical orbit around a star.