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]

The Collaborative International Dictionary of English v.0.48:

Gon \Gon\,
   imp. & p. p. of Go. [Obs.] --Chaucer.
   [1913 Webster]