Strong's G278 — ἀμεταμέλητος (adjective)
ametameletos (am-et-am-el'-ay-tos) adj.
1. irrevocable
[from G1 (as a negative particle) and a presumed derivative of G3338]
KJV: without repentance, not to be repented of 
Root(s): G1, G3338 
Hebrew root: μεταμέλλομαι
Occurrences: 2