The Collaborative International Dictionary
Cardecu
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.
Wiktionary
cardecu
n. (context historical English) A silver French coin worth a quarter of an écu.