Noun
(archaic, astronomy) A moon of a planet besides Earth; a secondary planet; a natural planetary satellite.
(astronomy) A planet viewed as a satellite of another object, such as another star; an exoplanet.
(astronomy) 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.
Source: en.wiktionary.orgI'd sooner exchange ideas with the birds on earth than learn to carry on intergalactic communications with some obscure race of humanoids on a satellite planet from the world of Betelgeuse. Edward Abbey