Strong’s Greek
G278 — ametameletos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἀμεταμέλητος
ametameletos — pronounced am-et-am-el'-ay-tos
from 1 (as a negative particle) and a presumed derivative of 3338; irrevocable:--without repentance, not to be repented of. see GREEK for 1 see GREEK for 3338
2 occurrences in the KJV.
Romans 11:29
For the gifts and calling of God are without repentance.
2 Corinthians 7:10
For godly sorrow worketh repentance to salvation not to be repented of: but the sorrow of the world worketh death.