148 entries under difficult topic. ×

10
strong(adjective, tough, energetic, powerful)
9
formidable(adjective, tough, severe, rough)
9
uphill(adjective, hard, great, tough, severe)
9
wearisome(adjective, dull, tough, severe)
8
heavy(adjective, dull, tough, severe, rough)
8
intense(adjective, strong, tough, harsh)
8
rugged(adjective, action, strong, tough, severe)
8
severe(adjective, tough, rough, harsh)
8
tireless(adjective, strong, energetic, lively)
8
trying(adjective, dull, tough, severe, rough)
8
wearying(adjective, dull, awkward, boring)
7
effortful(adjective, hard, great, tough, rough)
7
fatiguing(adjective, dull, awkward, boring)
7
operose(adjective, hard, tough, severe, rough)
7
powerful(adjective, strong, great, tough)
6
ardent(adjective, energetic, active, vigorous)
6
backbreaking(adjective, strong, hard, rough)
6
grueling(adjective, hard, tough, severe)
6
oppressive(adjective, dull, harsh, cruel)
6
rough(adjective, action, hard, great, tough)
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APASmart Define. (2016). strenuous thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/strenuous/thesaurus/synonyms
ChicagoSmart Define. 2016. "strenuous thesaurus" https://smartdefine.org/strenuous/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, strenuous thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/strenuous/thesaurus/synonyms>.
MLASmart Define. "strenuous thesaurus" 1 April 2016. Web. 23 September 2026. <https://smartdefine.org/strenuous/thesaurus/synonyms>