satellite planet

noun3

1. •
   A moon of planetary mass; a natural satellite which would be considered a planet or dwarf planet if it were in direct orbit of the Sun.
2. •
   A planet viewed as a satellite of another object, such as another star; an exoplanet.

   • It is possible that supernovae occur in conjunction with either a satellite planet or binary star. — 1970
3. •
   (no longer used) A moon of a planet besides Earth; a secondary planet; a natural planetary satellite.