255 entries under adjective topic. ×

6
devoted(strong, firm, determined, steady)
6
enduring(set, strong, fit, healthy)
6
faithful(resolute, tenacious)
6
insistent(resolute, tenacious)
6
laborious
6
stalwart(strong, sound, tough, fit)
6
undaunted
6
undeviating
6
zealous
5
active(strong, moving, difficult, energetic)
5
dedicated(strong, firm, determined, steady)
5
dynamic(strong, moving, lively, active)
5
earnest
5
hardworking
5
obstinate
5
perseverant
5
strong(sound, tough, fit, firm)
5
thorough
5
unceasing(strong, firm, determined, steady)
5
unyielding
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APASmart Define. (2015). indefatigable thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/indefatigable/thesaurus/synonyms
ChicagoSmart Define. 2015. "indefatigable thesaurus" https://smartdefine.org/indefatigable/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2015, indefatigable thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/indefatigable/thesaurus/synonyms>.
MLASmart Define. "indefatigable thesaurus" 10 April 2015. Web. 25 September 2026. <https://smartdefine.org/indefatigable/thesaurus/synonyms>