unalterable (
http://definr.com/unalterable)
adj 1: not capable of being changed or altered; "unalterable
resolve"; "an unalterable ground rule" [syn:
inalterable]
[ant:
alterable]
2: (law) of a sentence; that cannot be changed; "an unalterable
death sentence"
3: remaining the same for indefinitely long times [syn:
changeless]