cardecu UK /ˈkɑːdɪkjuː/US /ˈkɑɹdɪkju/ noun1 •(historical) A silver French coin worth a quarter of an écu.A set of hilding fellows there were, whom we dismissed to find them a new master — enough had been done for revenge and profit; the bunch of them were not worth a cardecu. — 1819 formscardecus