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
- Geo (automobile), a defunct brand of entry-level cars produced by General Motors
- 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.
- 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
| This disambiguation page lists articles associated with the title Geo.
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