2. Anachronistic usage: a star that wanders, or moves, in the sky.
3. A world that orbits a star or other celestial object. Primary planets our solar system include Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Secondary planets orbit primary planets. Earth and Pluto are binary planets. Secondary planets are some times called minor planets, but minor planets also include planets that does not orbit other planets. Pluto's status as a major or minor planet is debated.
Technically, there really isn't a definition for the word "Planet", atleast not in science. Planets can be described easily in dictionaries, but scientists question the definition. They don't have a real answer to what planets are and how to describe them, but that's why scientists are searching and discovering things about planet to have a REAL, CLEAN, and SCIENTIFIC definition for the term, Planet.