15
secure(verb, adjective, clear, sound, firm)
15
special(adjective, exact, extraordinary, superior, unusual)
15
unfailing(adjective, strong, true, reliable, trustworthy)
14
authentic(adjective, correct, honest, true, straight)
14
convinced(adjective, set, clear, firm, content)
14
destined(adjective, clear, hard, sound, plain)
14
true(adjective, good, strong, correct, firm)
13
conclusive(adjective, clear, strong, correct, easy)
13
distinct(adjective, clear, correct, firm, plain)
13
express(adjective, clear, complete, correct, total)
13
inescapable(adjective, near, regular, obvious, expected)
13
predestined(adjective, close, firm, near, sure)
13
set(adjective, change, clear, firm, solid)
13
settled(adjective, strong, easy, firm, solid)
13
trustworthy(adjective, good, clear, strong, sound)
13
understanding(noun, adjective, keen, sensible, alert)
13
undoubted(adjective, correct, firm, solid, physical)
12
cinch(noun, adjective, strong, easy, solid)
12
knowledge
12
legibility
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APASmart Define. (2016). certain thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/certain/thesaurus/synonyms
ChicagoSmart Define. 2016. "certain thesaurus" https://smartdefine.org/certain/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2016, certain thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/certain/thesaurus/synonyms>.
MLASmart Define. "certain thesaurus" 31 March 2016. Web. 22 September 2026. <https://smartdefine.org/certain/thesaurus/synonyms>