double planet

Noun

 * 1) a planet with a moon large enough to be considered a planet, were the planet not there, having a substantial portion of the system's overall mass.
 * 2) a pair of planemos in orbit around each other, where the barycenter of their orbits lies outside of both planemos, which in turn is in orbit about a star.
 * 3) a pair of planemos in orbit around each other, where the barycenter of their orbits lies outside of both planemos.
 * 4) a planemo with a moon large enough to be considered a planemo, having a substantial portion of the system's overall mass.