Source : Webster's Revised Unabridged Dictionary (1913)

Gainsay \Gain`say"\ (? or ?; 277), v. t. [imp. & p. p.
   {Gainsaid} (? or ?); p. pr. & vb. n. {Gainsaying}.] [OE.
   geinseien, ageinseien. See {Again}, and {Say} to utter.]
   To contradict; to deny; to controvert; to dispute; to forbid.

         I will give you a mouth and wisdom which all your
         adversaries shall not be able to gainsay nor resist.
                                                  --Luke xxi.
                                                  15.

         The just gods gainsay That any drop thou borrow'dst
         from thy mother, My sacred aunt, should by my mortal
         sword Be drained.                        --Shak.