1
staunch
1
steady
1
steely(adjective, strong, hard, tough, severe)
1
stony
1
strong(adjective, hard, tough, firm, determined)
1
strongheaded
1
sturdy(adjective, strong, hard, tough, firm)
1
sulky
1
swinish
1
thick-skinned(adjective, mean, hard, harsh, inflexible)
1
tough-nut(adjective, hard, tough, difficult, wild)
1
tough nut(expression, sharp, determined, practical, shrewd)
1
tough nut to crack(expression, adjective, idiom, mean, hard)
1
unadaptable
1
unappeasable(adjective, determined, resolute, uncompromising, unshakeable)
1
uncompassionate(adjective, mean, hard, harsh, inflexible)
1
uncompliant(adjective, stubborn)
1
uncontrollable(determined, impulsive, stubborn, reckless, impetuous)
1
undisciplined(tough, difficult, awkward, obstinate, stubborn)
1
unflagging
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APASmart Define. (2015). mulish thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/mulish/thesaurus/synonyms
ChicagoSmart Define. 2015. "mulish thesaurus" https://smartdefine.org/mulish/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2015, mulish thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/mulish/thesaurus/synonyms>.
MLASmart Define. "mulish thesaurus" 13 April 2015. Web. 25 September 2026. <https://smartdefine.org/mulish/thesaurus/synonyms>