Adjective
Not alterable; incapable of being altered or changed; unalterable.
Source: Webster's dictionaryWere it not for this inalterable armony, pre-established by God, between subject and object, all our thinking would be necessarily without fruit. Julius Robert von Mayer
We're facing a radical ideology with inalterable objectives: to enslave whole nations and intimidate the world. No act of ours invited the rage of the killers - and no concession, bribe, or act of appeasement would change or limit their plans for murder. George W. Bush
unalterable resolve Source: Internet
an unalterable ground rule Source: Internet