65 entries under rigid topic. ×

5
stern(adjective, resolute)
4
indomitable(adjective, hard, resolute, inflexible)
4
relentless(adjective, hard, resolute, inflexible)
4
static(set, regular, fixed, constant)
4
tough(adjective, calm, strong, solid, substantial)
3
iron(adjective, set, hard, stiff)
3
strict(adjective, strong, hard, certain, definite)
3
unrelenting(adjective, hard, resolute, inflexible)
2
adamantine(hard, resolute, inflexible, strict)
2
dyed-in-the-wool(adjective, hard, resolute, inflexible)
2
exact(adjective, strong, certain, definite)
2
hard-and-fast(adjective, set, hard, certain, stiff)
2
severe
2
unadaptable(adjective, set, hard, stiff)
2
unfailing(set, clear, certain, regular, definite)
1
austere
1
concrete
1
harsh
1
stringent(adjective, set, hard, stiff)
1
taut
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APASmart Define. (2015). unchangeable thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/unchangeable/thesaurus/synonyms
ChicagoSmart Define. 2015. "unchangeable thesaurus" https://smartdefine.org/unchangeable/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2015, unchangeable thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/unchangeable/thesaurus/synonyms>.
MLASmart Define. "unchangeable thesaurus" 3 August 2015. Web. 27 September 2026. <https://smartdefine.org/unchangeable/thesaurus/synonyms>