Abbott-Smith Manual Greek Lexicon
σκληρύνω (G4645)
6 σκληρύνω ( σκληρός ), [in LXX chiefly for קשׁה hi., also for חזק ;] to harden . Metaph., to harden, make stubborn : c. acc. pers., Ro 9:18 ; τ. καρδίας ( Ps 94 (95):8 ), He 3:8 , 15 4:7 . Pass., to become hardened : Ac 19:9 , He 3:13 .†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain