Abbott-Smith Manual Greek Lexicon
κρυφῇ (G2931)
1 κρυφῇ (prop. -ῆ , Rec.; later spelling is due to assimilation to dat.; cf. εἰκῆ ), adv. , [in LXX chiefly for סתר ;] secretly , in secret : Eph 5:12 .†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain