GEOS may refer to:

• GEOS (8-bit operating system), an operating system originally designed for the Commodore 64
• GEOS (16-bit operating system), a DOS-based graphical user interface and x86 operating system
• GEOS (securities processing software), an integrated online system for the management and processing of securities
• GEOS (software library), an open-source geometry engine
• Goddard Earth Observing System, an Earth system model

• GEOS (eikaiwa), an English conversation teaching company based in Japan
• GEOS circle, an intersection of four lines that are associated with a generalized triangle
• GEOS (satellite), a research satellite from ESRO (1978–1982)
• GEOS (satellite series), three research satellites from NASA
• Groupe GEOS, a French business consultancy

This disambiguation page lists articles associated with the title GEOS.
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