DuckCorp Dico

Found one definition

1.                 From The Collaborative International Dictionary of English v.0.48:
                   
   
   
                   
                     
   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.
      [1913 Webster]