Strong's G2589 — καρδιογνώστης (noun)
kardiognostes (kar-dee-og-noce'-tace) n.
1. a heart-knower
[from G2588 and G1097]
KJV: which knowest the hearts 
Root(s): G2588, G1097 
Hebrew root: γινώσκω
Occurrences: 2