(astronomy, planets) Any planet of the Solar System whose orbit is located between the asteroid belt and the sun, i.e., any of Mercury, Venus, Earth, or Mars.

(astronomy) Any planet of the Solar System whose orbit is located beyond the asteroid belt, i.e., any of Jupiter, Saturn, Uranus, or Neptune.

(astronomy) An astronomical object in direct orbit around the Sun that is not a planet or a comet.

Anyone who wishes to save the environment with an ambitious plan.

(uncommon) Those things that are planets; the state of being a planet.

Alternative form of exoplanet

Any planet of the solar system or any exoplanet which is "Earth-like" in the sense that it is composed primarily of metals and rock, in contrast to a planet which is a gas giant.

(astronomy) A nebulosity surrounding a dying red giant, consisting of material expelled by the star.

plural of planetary ring

Someone interested in planespotting.