DuckCorp Dico

Found one definition

1.                 From The Jargon File (version 4.4.7, 29 Dec 2003):
                   
   
   
                   
                     
   FSF
    /F·S·F/, abbrev.
       Common abbreviation (both spoken and written) for the name of the Free
       Software Foundation, a nonprofit educational association formed to support
       the GNU project.