κέκυφα

From LSJ

τὸ γὰρ εὖ πράττειν παρὰ τὴν ἀξίαν ἀφορμὴ τοῦ κακῶς φρονεῖν τοῖς ἀνοήτοις γίγνεται → undeserved success engenders folly in unbalanced minds

Source

French (Bailly abrégé)

v. κύπτω.

Dutch (Woordenboekgrieks.nl)

κέκυφα perf. van κύπτω.

Russian (Dvoretsky)

κέκῡφα: pf. к κύπτω.