Abbott-Smith Manual Greek Lexicon
πεποίθησις (G4006)
6 † πεποίθησις , -εως, ἡ ( πείθω ), [in LXX: IV Ki 18:19 ( בִּטָּחוֹן )*;] confidence : II Co 1:15 3:4 10:2 , Eph 3:12 ; seq. εἰς , II Co 8:22 ; ἐν , Phl 3:4 (the word is condemned by the Atticists, v. Rutherford, NPhr. , 355).†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain