Strong's G4641 — σκληροκαρδία (noun)
sklerokardia (sklay-rok-ar-dee'-ah) n.
1. hard-heartedness
2. (specially), destitution of (spiritual) perception
[feminine of a compound of G4642 and G2588]
KJV: hardness of heart 
Root(s): G4642, G2588 
Hebrew root: καρδία
Occurrences: 3