is a specific kind of: quality.

is a broader term that covers: absoluteness | constancy, stability | innateness | irreversibility | invariability, invariableness, invariance | fixedness, unalterability | unexchangeability | fixity, immutability, immutableness.

is the opposite of: changeability, changeableness.

derivation: unchangeable | changeless, unalterable | stable, static, unchanging | changeless, immutable | unchanging.