3
inexhaustibly
3
intently(adverb, resolutely)
3
steadfastly(adverb, tenaciously)
2
arduously(adverb, vigorously, earnestly, actively, hastily)
2
boldly(adverb, resolutely, tenaciously)
2
ceaselessly(adverb, continuously)
2
constantly(adverb, continuously)
2
continuously(adverb, continuously)
2
courageously(adverb, resolutely, tenaciously)
2
dauntlessly(adverb, resolutely, tenaciously)
2
decisively(adverb, resolutely, tenaciously)
2
everlastingly(adverb, continuously)
2
patiently
2
perseveringly(adverb, vigorously, earnestly, hastily, carefully)
2
pluckily(adverb, resolutely, tenaciously)
2
purposefully(vigorously, earnestly, hastily, carefully, strictly)
2
relentlessly(adverb, resolutely)
2
staunchly(adverb, resolutely, tenaciously)
2
steadily(adverb, continuously, resolutely)
2
stubbornly(adverb, resolutely, tenaciously)
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APASmart Define. (2016). indefatigably thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/indefatigably/thesaurus/synonyms
ChicagoSmart Define. 2016. "indefatigably thesaurus" https://smartdefine.org/indefatigably/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2016, indefatigably thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/indefatigably/thesaurus/synonyms>.
MLASmart Define. "indefatigably thesaurus" 24 March 2016. Web. 24 September 2026. <https://smartdefine.org/indefatigably/thesaurus/synonyms>