- unalterable, inalterable - not capable of being changed or altered; "unalterable resolve"; "an unalterable ground rule"
Antonym: alterable
- unalterable - of a sentence; that cannot be changed; "an unalterable death sentence"
Antonym: commutable (indirect, via incommutable)
- changeless, unalterable - remaining the same for indefinitely long times
Antonyms: changeable, changeful (indirect, via unchangeable)