BSD

BSD /B-S-D/ n.  [abbreviation for `Berkeley Software
   Distribution'] a family of {{UNIX}} versions for the {DEC}
   {VAX} and PDP-11 developed by Bill Joy and others at
   {Berzerkeley} starting around 1980, incorporating paged virtual
   memory, TCP/IP networking enhancements, and many other features.
   The BSD versions (4.1, 4.2, and 4.3) and the commercial versions
   derived from them (SunOS, ULTRIX, and Mt. Xinu) held the technical
   lead in the UNIX world until AT&T's successful standardization
   efforts after about 1986, and are still widely popular.  Note that
   BSD versions going back to 2.9 are often referred to by their
   version numbers, without the BSD prefix.  See {4.2}, {{UNIX}},
   {USG UNIX}.