Unalterable
(adjective)
Not capable of being changed or modified.
Origin:
From un- + alterable.
Examples:
- The laws of physics are unalterable.
- His unalterable resolve was evident in the way he held himself.
- The unalterable decision of the court was final.
- The unalterable facts of the case were clear.
- His unalterable opinion on the matter was well known.