GEO

(1) Geostationary Earth Orbit (2) Geodetic Reference System (3) Geosynchronous Earth Orbiting (4) A prefix meaning "earth" as in "geology", "geophisics". Most writers use the established terms such as "geology" to refer to the same concept on other bodies of the solar system, as "the geology of Mars", rather than "areology" or "marsology", "geology of the moon", rather than "selenology".