Source : Webster's Revised Unabridged Dictionary (1913)

Cardecu \Car"de*cu\ (k[aum]r"d[-e]*k[-u]), n. [Corrupt, from F.
   quart d'['e]cu.]
   A quarter of a crown. [Obs.]

         The bunch of them were not worth a cardecu. --Sir W.
                                                  Scott.