Any of the four gas giant planets in the Solar System: Jupiter, Uranus, Saturn, or Neptune.

(astronomy) A hypothetical planet in the Solar system, beyond the currently known outermost planet. (The term was applied to Eris for a short while, when Pluto was still considered the ninth planet.)

(astronomy) A world-like planetoid of the Solar system, that is smaller than the classical planets. More specifically, any astronomical body which has a geology defined by hydrostatic equilibrium (and thus has taken the shape a body of water would take, as opposed to a small Solar System body), orbits the Sun (as opposed to a moon), and does not gravitationally dominate other bodies near its orbit (as opposed to a classical planet or, in IAU usage, as opposed to a planet).

plural of Trojan planet

(astronomy, celestial mechanics) An imaginary celestial body (corresponding to another, real, orbiting one) which orbits with constant speed along an auxiliary circle (a circle which shares a diameter with the major axis of the elliptical orbit of the corresponding real celestial body), such that its position coincides with the position of the corresponding, real celestial body when that body passes through periapsis.

plural of interstellar planet

(archaic) Afflicted by the astrological influence of a planet; struck down with amazement or shock; panic-stricken.

Synonym of planet-struck

(astronomy, planetology) a planetary-mass object which has either been ejected from its system or was never gravitationally bound to any star or other such object, and that therefore orbits the galaxy directly.

plural of planet wheel