38 entries under stiff topic. ×

32
inflexible(adjective, strong, hard, tough, firm)
30
unyielding(adjective, strong, hard, tough, firm)
28
tough(adjective, strong, hard, firm, unreasonable)
26
rigid(adjective, strong, hard, tough, severe)
25
unbreakable(adjective, strong, tough, severe, firm)
21
hard(adjective, strong, strength, tough, firm)
21
impenetrable(adjective, set, tough, firm)
20
firm(adjective, strong, hard, tough, determined)
13
stony(adjective, firm, rigid, stubborn)
12
iron(adjective, set, strong, hard, tough)
9
rocky(adjective, set, firm, compact)
8
set(adjective, severe, firm, harsh, determined)
6
hardened(adjective, strong, firm, determined)
6
strong(adjective, set, hard, strength, tough)
5
rigorous(adjective, set, strong, hard, tough)
4
bullheaded(adjective, strong, hard, tough, severe)
4
solid(adjective, set, strong, hard, severe)
3
indurate(adjective, set, firm, determined)
2
dense(adjective, set, strong, hard, tough)
2
durable(adjective, strong, tough, firm)
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APASmart Define. (2015). adamantine thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/adamantine/thesaurus/synonyms
ChicagoSmart Define. 2015. "adamantine thesaurus" https://smartdefine.org/adamantine/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2015, adamantine thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/adamantine/thesaurus/synonyms>.
MLASmart Define. "adamantine thesaurus" 10 April 2015. Web. 25 September 2026. <https://smartdefine.org/adamantine/thesaurus/synonyms>