1
explicit(adjective, strong, complete, flat, total)
1
express(adjective, complete, total, definite, absolute)
1
faithful(adjective, intense, certain, resolute, persistent)
1
flat out(expression, adjective, complete, total, definite)
1
foolproof(adjective, infallible)
1
for a fact(expression, adjective, idiom, clear, certain)
1
free from doubt(expression, adjective, idiom, clear, certain)
1
genuine(adjective, set, clear, complete, warm)
1
hang tough(expression, adjective, strong, certain, definite)
1
immortal
1
immovable(adjective, firm, solid, intense, stable)
1
imperturbable(adjective, firm, solid, stable, fixed)
1
in the bag(expression, adjective, idiom, certain, limited)
1
inalterable(adjective, certain, limited, definite, inflexible)
1
incontestable(adjective, clear, certain, definite, positive)
1
incontrovertible(adjective, clear, certain, definite, positive)
1
indisputable(adjective, clear, certain, definite, positive)
1
indubitable(adjective, clear, certain, definite, positive)
1
inerrant(certain, unquestionable, undisputable)
1
inescapable(certain, unquestionable, undisputable)
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APASmart Define. (2015). never-failing thesaurus. Retrieved September 30, 2026, from https://smartdefine.org/never-failing/thesaurus/synonyms
ChicagoSmart Define. 2015. "never-failing thesaurus" https://smartdefine.org/never-failing/thesaurus/synonyms (accessed September 30, 2026).
HarvardSmart Define 2015, never-failing thesaurus, Smart Define, viewed 30 September, 2026, <https://smartdefine.org/never-failing/thesaurus/synonyms>.
MLASmart Define. "never-failing thesaurus" 14 April 2015. Web. 30 September 2026. <https://smartdefine.org/never-failing/thesaurus/synonyms>