geoTheo v1.1 - "A concise thesaurus for GEOS", by Bret M. Timmins (NewSpeak Software).  The following is a quote from the manual:

Welcome to geoTheo. The first thesaurus written specifically for the GEOS environment. Unlike a traditional thesaurus in book format, where precious time is wasted thumbing through a long index, geoTheo gives you nearly instant access to thousands of the most commonly used--and misused -- synonyms by simply typing a word.

Thanks to Bruce Thomas for sending over this neat GEOS Desk Accessory that works in both GEOS 64 and GEOS 128 (40 or 80 column mode).  geoTheo was announced in the August 1991 issue of RUN magazine and Bruce purchased a copy in November 1991.  In September of 2004 Bruce contacted Bret Timmins resulting in the public domain release of the program.  In this archive you will find the disk image containing the program and the advertised 10,000 word data file, plus a geoWrite file of the manual and a PDF of the printed version which Bruce scanned in.