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

fourth generation language
4GL

    (4GL, or "report generator language") An
   "application specific" language, one with built-in knowledge
   of an application domain, in the way that SQL has built-in
   knowledge of the relational database domain.

   The term was invented by Jim Martin to refer to
   non-procedural high level languages built around
   database systems.

   Fourth generation languages are close to natural language
   and were built with the concept that certain applications
   could be generalised by adding limited programming ability to
   them.

   When given a description of the data format and the report to
   generate, a 4GL system produces COBOL (or other 3GL) code,
   that actually reads and processes the data and formats the
   results.

   Some examples of 4GL are: database query language e.g.SQL;
   Focus, Metafont, PostScript, S, IDL-PV, WAVE,
   Gauss, Mathematica, and data-stream languages such as
   AVS, APE, Iris Explorer.

   (2004-04-01)