Strong’s Greek
G279 — ametanoetos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἀμετανόητος
ametanoetos — pronounced am-et-an-o'-ay-tos
from 1 (as a negative particle) and a presumed derivative of 3340; unrepentant:--impenitent. see GREEK for 1 see GREEK for 3340
1 occurrence in the KJV.
Romans 2:5
But after thy hardness and impenitent heart treasurest up unto thyself wrath against the day of wrath and revelation of the righteous judgment of God;