V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

3GL
       3rd Generation Language


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

third generation language
3GL

    (3GL, "high level language") A language designed
   to be easier for a human to understand, including things like
   named variables.  A fragment might be

   	let c = c + 2 * d

   Fortran, ALGOL and COBOL are early examples of this sort of
   language.  Most "modern" languages (BASIC, C, C++) are
   third generation.  Most 3GLs support structured programming.

   See also second generation language, fourth generation
   language.

   (1996-05-30)