255 entries under adjective topic. ×

3
enthusiastic(determined, active, resolute, peppy)
3
fervent
3
hearty(strong, fit, healthy, well)
3
inexorable
3
lively(strong, moving, active, vigorous)
3
obdurate
3
plodding(activity, strong, firm, determined)
3
plucky(resolute, tenacious)
3
set
3
tough(strong, sound, fit, firm)
3
unbending
3
unconquerable
3
undying
3
unshakeable
3
vital(strong, tough, fit, lively)
2
aggressive(strong, moving, lively, active)
2
ambitious
2
animated(strong, moving, lively, active)
2
brisk(strong, moving, lively, active)
2
careful
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APASmart Define. (2015). indefatigable thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/indefatigable/thesaurus/synonyms
ChicagoSmart Define. 2015. "indefatigable thesaurus" https://smartdefine.org/indefatigable/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2015, indefatigable thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/indefatigable/thesaurus/synonyms>.
MLASmart Define. "indefatigable thesaurus" 10 April 2015. Web. 26 September 2026. <https://smartdefine.org/indefatigable/thesaurus/synonyms>