Something that cannot be changed.

Unable to be changed without exception. / (programming, of a variable) Not able to be altered in the memory after its value is set initially.

The state of being immutable; unchangeableness.

plural of immutable

In an immutable manner. In a way that cannot be varied, or changed.

(obsolete) unchanged

The state or quality of being immutable; immutableness. / (computing) The state of being unchangeable in the memory after creation.

plural of immutability

plural of immutation

change; alteration; mutation