Source : Webster's Revised Unabridged Dictionary (1913)

Gammer \Gam"mer\ (g[a^]m"m[~e]r), n. [Possibly contr. fr.
   godmother; but prob. fr. grammer for grandmother. Cf.
   {Gaffer}.]
   An old wife; an old woman; -- correlative of {gaffer}, an old
   man.