Strong's G531 — ἀπαράβατος (adjective)
aparabatos (ap-ar-ab'-at-os) adj.
1. not passing away, i.e. untransferable (perpetual)
[from G1 (as a negative particle) and a derivative of G3845]
KJV: unchangeable 
Root(s): G1, G3845 
Hebrew root: παραβαίνω
Occurrences: 1