Immutable (adjective)

1. Not able to be changed or altered.
2. Permanently fixed or established.

Origin:

From latin immutabilis, from in- + mutabilis changeable.

Examples:

1. The laws of physics are immutable, they cannot be changed.
2. The company's policy on employee benefits is immutable.
3. The team's record for the most victories in a season is immutable.
4. The Constitution of the country is immutable, it cannot be altered without a formal process.
5. His decision on this matter is immutable, he will not change his mind.