69 entries under firm topic. ×

8
refractory(adjective, tough, difficult, determined)
8
stiff-necked(adjective, tough, resist, determined)
8
unwavering(adjective, strong, determined, steady)
7
tireless(adjective, strong, energetic, determined)
7
unfaltering(adjective, strong, energetic, determined)
7
unshakable(adjective, tough, determined, resolute)
6
fixed(adjective, tough, determined, resolute)
6
self-willed(adjective, tough, difficult, determined)
6
unflagging(adjective, strong, energetic, determined)
6
unswerving(adjective, strong, tough, determined)
5
staunch(adjective, strong, tough, determined)
5
unfailing(adjective, strong, determined, steady)
4
constant(adjective, strong, determined, active)
4
indomitable(adjective, strong, tough, difficult)
4
patient(adjective, strong, energetic, determined)
4
single-minded(adjective, tough, determined, resolute)
4
tough(adjective, determined, resolute, obstinate)
3
plodding(adjective, strong, determined, steady)
3
recalcitrant(adjective, tough, difficult, awkward)
3
steady(adjective, strong, determined, resolute)
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APASmart Define. (2015). pertinacious thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/pertinacious/thesaurus/synonyms
ChicagoSmart Define. 2015. "pertinacious thesaurus" https://smartdefine.org/pertinacious/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2015, pertinacious thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/pertinacious/thesaurus/synonyms>.
MLASmart Define. "pertinacious thesaurus" 10 April 2015. Web. 24 September 2026. <https://smartdefine.org/pertinacious/thesaurus/synonyms>