19
well-balanced(adjective, strain, firmness, labour, hardiness)
18
relentless(adjective, strong, tough, firm, determined)
18
robust(adjective, strain, firmness, labour, hardiness)
18
tireless(adjective, determined, resolute, tenacious)
18
unrelenting(adjective, certain, determined, resolute, persistent)
17
devoted(adjective, good, close, strong, kind)
17
indefatigable(adjective, resolute, persevering, tenacious, untiring)
16
dependable(adjective, good, close, strong, correct)
16
reliable(adjective, calm, close, strong, secure)
16
unflagging(adjective, perseverance, persevering, tenacious)
15
dedicated(adjective, clear, kind, tough, severe)
15
sure(adjective, calm, good, close, strong)
15
unbendable(adjective, determined, resolute, obstinate, uncompromising)
15
unchanging(adjective, close, correct, firm, honest)
14
abiding(adjective, calm, strong, complete, secure)
14
solid(adjective, calm, good, strong, secure)
13
unchangeable(adjective, calm, strong, secure, flat)
13
undeviating(adjective, strong, flat, firm, solid)
12
changeless(adjective, firm, solid, certain, steady)
12
immutable(adjective, calm, strong, secure, firm)
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APASmart Define. (2016). steadfast thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/steadfast/thesaurus/synonyms
ChicagoSmart Define. 2016. "steadfast thesaurus" https://smartdefine.org/steadfast/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2016, steadfast thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/steadfast/thesaurus/synonyms>.
MLASmart Define. "steadfast thesaurus" 11 March 2016. Web. 21 September 2026. <https://smartdefine.org/steadfast/thesaurus/synonyms>