2
negating(verb, confuting)
2
obstinate(adjective, defiant)
2
onerous(adjective, hard, great, tough, severe)
2
probing(verb, adjective, questioning)
2
problematical(adjective, difficult, awkward, demanding, tricky)
2
rebelling(verb, defying)
2
recalcitrant(adjective, defiant)
2
refuting(verb, confuting)
2
resistant(adjective, unwilling, opposed, defiant)
2
rugged(adjective, difficult, awkward, demanding, grueling)
2
spunky
2
stimulant(adjective, offensive, stimulating, disturbing, provoking)
2
stirring
2
strenuous(adjective, great, tough, severe, difficult)
2
titanic(tough, severe, painful, problematic, trying)
2
toilsome(adjective, great, tough, severe, difficult)
2
tough(adjective, great, severe, difficult, painful)
2
unyielding(adjective, tough, severe, painful, problematic)
1
abnegating(verb, confuting)
1
abrogating(verb, confuting)
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APASmart Define. (2016). challenging thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/challenging/thesaurus/synonyms
ChicagoSmart Define. 2016. "challenging thesaurus" https://smartdefine.org/challenging/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2016, challenging thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/challenging/thesaurus/synonyms>.
MLASmart Define. "challenging thesaurus" 2 March 2016. Web. 22 September 2026. <https://smartdefine.org/challenging/thesaurus/synonyms>