The Collaborative International Dictionary of English v.0.48:

Gan \Gan\, imp. of Gin. [See Gin, v.]
   Began; commenced.
   [1913 Webster]

   Note: Gan was formerly used with the infinitive to form
         compound imperfects, as did is now employed. Gan
         regularly denotes the singular; the plural is usually
         denoted by gunne or gonne.
         [1913 Webster]

               This man gan fall (i.e., fell) in great
               suspicion.                         --Chaucer.
         [1913 Webster]

               The little coines to their play gunne hie (i. e.,
               hied).                             --Chaucer.
         [1913 Webster]

   Note: Later writers use gan both for singular and plural.
         [1913 Webster]

               Yet at her speech their rages gan relent.
                                                  --Spenser.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Gin \Gin\ (g[i^]n), v. i. [imp. & p. p. Gan (g[a^]n), Gon
   (g[o^]n), or Gun (g[u^]n); p. pr. & vb. n. Ginning.] [OE.
   ginnen, AS. ginnan (in comp.), prob. orig., to open, cut
   open, cf. OHG. inginnan to begin, open, cut open, and prob.
   akin to AS. g[imac]nan to yawn, and E. yawn. [root]31. See
   Yawn, v. i., and cf. Begin.]
   To begin; -- often followed by an infinitive without to; as,
   gan tell. See Gan. [Obs. or Archaic] "He gan to pray."
   --Chaucer.
   [1913 Webster]

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

GAN
       Global Area Network


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

GAN
       GrenzAktenNachweis (INPOL)


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

GAN

   Generating and Analyzing Networks.  "GAN - A System for
   Generating and Analyzing Activity Networks", A. Schurmann,
   CACM 11(10) (Oct 1968).