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

POSTGRES

    An active DBMS developed at the University of
   California at Berkeley by a team led by Michael Stonebraker
   (1986-1994).  Postgres was later taken by Illustra and
   developed into a commercial product, which in turn was bought
   by Informix and integrated into their product, Universal
   Server.

   PostgreSQL is a further development of the original POSTGRES
   code as a free software alternative to commercial DBMS
   vendor offerings.

   [Details?  Reference?  Relationship to Ingres?]

   (1999-07-04)