10
steady(adjective, calm, strong, secure, firm)
9
indestructible(adjective, stable, constant, enduring, unable)
9
unvarying(adjective, calm, strong, secure, firm)
8
consistent(adjective, dull, steady, stable, regular)
8
even(adjective, calm, strong, secure, firm)
8
resolute(adjective, calm, strong, hard, determined)
8
rigid(adjective, set, hard, regular, fixed)
7
irreversible(adjective, fixed, even, rigid, inflexible)
7
unchanged(adjective, fixed, static, unvarying, unchangeable)
7
unwavering(adjective, calm, set, strong, solid)
6
durable(adjective, calm, strong, solid, steady)
6
immovable(adjective, set, hard, steady, regular)
6
inalterable(adjective, inflexible, flexible)
6
obstinate(adjective, set, strong, hard, severe)
6
stubborn(adjective, firm, steady, fixed, rigid)
6
undeviating(adjective, even, constant, rigid, inflexible)
5
adamant(adjective, hard, firm, fixed, inflexible)
5
hard(adjective, resolute, rigid, inflexible, strict)
5
irrevocable(adjective, fixed, unchangeable)
5
perennial(adjective, stable, constant, stability, enduring)
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APASmart Define. (2015). immutable thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/immutable/thesaurus/synonyms
ChicagoSmart Define. 2015. "immutable thesaurus" https://smartdefine.org/immutable/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, immutable thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/immutable/thesaurus/synonyms>.
MLASmart Define. "immutable thesaurus" 10 April 2015. Web. 22 September 2026. <https://smartdefine.org/immutable/thesaurus/synonyms>