Strong’s Greek
G276 — ametathetos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἀμετάθετος
ametathetos — pronounced am-et-ath'-et-os
from 1 (as a negative particle) and a derivative of 3346; unchangeable, or (neuter as abstract) unchangeability:--immutable(-ility). see GREEK for 1 see GREEK for 3346
2 occurrences in the KJV.
Hebrews 6:17
Wherein God, willing more abundantly to shew unto the heirs of promise the immutability of his counsel, confirmed it by an oath:
Hebrews 6:18
That by two immutable things, in which it was impossible for God to lie, we might have a strong consolation, who have fled for refuge to lay hold upon the hope set before us: