Meaning : Not capable of being changed or altered.
Example :
Unalterable resolve.
An unalterable ground rule.
Synonyms : inalterable
Capable of being changed or altered in some characteristic.
Alterable clothing.Meaning : Of a sentence. That cannot be changed.
Example :
An unalterable death sentence.
Meaning : Remaining the same for indefinitely long times.
Synonyms : changeless