Geo

GEO or Geo can mean any of these:
 GEO (magazine), a popular scientific magazine
 GEO 600, a detector for gravitational radiation
 Global Environment Outlook, an environmental assessment produced by the United Nations
 Geo (microformat), a microformat for marking up WSG84 geographical coordinates in (X)HTML

In shopping:
 Geo (automobile), a defunct brand of entry-level cars produced by General Motors

People:
 Geo. is sometimes an abbreviation of the name George.
 Geo, the composer for the J-pop group Sweetbox
 Geo (artist), the Korean manhwa artist.
 Geo Bogza, a Romanian poet and essayist.
 Geo Stelar is the main protagonist in Mega Man Star Force.

In science:
 Geography, the study of the Earth and its features
 Geology, the study of the Earth's structure
 Geothermal (geology), heat sources from within the Earth
 Geometry, the study of spatial relationships