19 entries under infallible topic. ×

11
unfailing
11
reliable
10
sure
9
dependable
9
flawless(adjective, correct, clean, perfect, pure)
8
certain(adjective, flawless, faultless, textbook)
8
sure-fire(adjective, dependable)
7
fail-safe(adjective, fail, thrive)
7
faultless(adjective, perfect, pure, splendid, flawless)
7
goofproof(verb, adjective)
7
guaranteed
7
safe
6
perfect(adjective, correct, clean, pure, flawless)
4
unerring(adjective, flawless, faultless, textbook)
2
tested
2
tried
2
unassailable
1
idiot-proof
1
never-failing
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APASmart Define. (2015). foolproof thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/foolproof/thesaurus/synonyms
ChicagoSmart Define. 2015. "foolproof thesaurus" https://smartdefine.org/foolproof/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, foolproof thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/foolproof/thesaurus/synonyms>.
MLASmart Define. "foolproof thesaurus" 14 April 2015. Web. 22 September 2026. <https://smartdefine.org/foolproof/thesaurus/synonyms>