Strong’s Greek
G531 — aparabatos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἀπαράβατος
aparabatos — pronounced ap-ar-ab'-at-os
from 1 (as a negative particle) and a derivative of 3845; not passing away, i.e. untransferable (perpetual):-- unchangeable. see GREEK for 1 see GREEK for 3845
1 occurrence in the KJV.
Hebrews 7:24
But this man, because he continueth ever, hath an unchangeable priesthood.