i-mu-ta-bil'-i-ti, i-mu'-ta-b'-l (ametathetos):
Occurs in Hebrews 6:17,18 of the unchangeableness of the Divine counsel. It is the perfection of Yahweh that He changes not in character, will, purpose, aim (Malachi 3:6; so of Christ, Hebrews 13:8).
See FAITHFULNESS; UNCHANGEABLE.