Source : Webster's Revised Unabridged Dictionary (1913)

Dupe \Dupe\, v. t. [imp. & p. p. {Duped}; p. pr. & vb. n.
   {Duping}.] [Cf. F. duper, fr. dupe. See {Dupe}, n.]
   To deceive; to trick; to mislead by imposing on one's
   credulity; to gull; as, dupe one by flattery.

         Ne'er have I duped him with base counterfeits. --
                                                  Coleridge.