σκληρύνω
(σκληρός), [in LXX chiefly for קָשָׁה hi., also for חָזַק ;]
to harden. Metaphorical, to harden, make stubborn: with accusative of person(s), Rom.9:18; T. καρδίας (Psa.95:8), Heb.3:8, 15 4:7. Pass., to become hardened: Act.19:9, Heb.3:13.†
(AS)