144 entries under tough topic. ×

11
viscous(adjective, secure, thick, tacky)
10
adhesive(adjective, secure, thick, tacky)
10
headstrong(adjective, firm, resist, awkward)
10
indomitable(adjective, strong, firm, difficult)
10
sturdy(adjective, strong, sound, fit)
9
fast(adjective, strong, free, secure)
9
inexorable(adjective, firm, determined, resolute)
9
pigheaded(adjective, firm, difficult, resist)
8
hardheaded(adjective, firm, resist, determined)
8
single-minded(adjective, intense, deliberate, determined)
8
stout(adjective, strong, sound, fit)
8
unshakable(adjective, strong, firm, determined)
8
vigorous(adjective, strong, sound, fit)
8
viscid(adjective, secure, tacky, sticky)
7
bullheaded(adjective, firm, difficult, resist)
7
constant(adjective, strong, flat, firm)
7
enduring(adjective, strong, sound, fit)
7
hearty(adjective, strong, sound, fit)
7
plucky(adjective, strong, determined, bold)
7
secure(adjective, strong, sound, free)
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APASmart Define. (2015). tenacious thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/tenacious/thesaurus/synonyms
ChicagoSmart Define. 2015. "tenacious thesaurus" https://smartdefine.org/tenacious/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2015, tenacious thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/tenacious/thesaurus/synonyms>.
MLASmart Define. "tenacious thesaurus" 6 November 2015. Web. 27 September 2026. <https://smartdefine.org/tenacious/thesaurus/synonyms>