V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

GEOS
       Graphic Environment Operating System (OS)


The Free On-line Dictionary of Computing (30 December 2018):

GEOS

   A small windowing, microkernel (less than 64 kbytes long)
   operating system written in heavily bummed assembly
   language for MS-DOS computers.  It multitasks rather
   nicely on a 6 Mhz Intel 80286 with at least 512K memory.

   It was adapted to PDAs by adding pen recognition, which
   doesn't work very well.

   Usenet newsgroup: news:comp.os.geos.

   (1995-01-21)