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

knowledge-based system

    (KBS) A program for extending and/or
   querying a knowledge base.

   The related term expert system is normally used to refer to
   a highly domain-specific type of KBS used for a specialised
   purpose such as medical diagnosis.

   The Cyc project is an example of a large KBS.

   (1999-09-07)