4
unpleasant(adjective, bad)
4
unscientific(adjective, reasoning, worthless, unfounded)
4
unusable(adjective, useless, unfit, inapplicable)
4
vain(adjective, void, unsound, trifling, petty)
3
absurd(adjective, foolish, unreasonable, fantastic, absurd)
3
annulled(adjective, canceled)
3
baseless(adjective, foolish, unreasonable, worthless, unacceptable)
3
bootless
3
crazy(adjective, foolish, unreasonable, absurd, illogical)
3
diseased(mean, weak, down, sick, feeble)
3
foolish(adjective, unreasonable, fantastic, absurd, irrational)
3
futile
3
handicapped(adjective, poor, inadequate, ineffective, ineffectual)
3
helpless(adjective, incompetent, vulnerable, incapable)
3
ill-suited(adjective, bad, useless, unfit)
3
implausible(adjective, poor, false, unreasonable, inadequate)
3
impracticable(adjective, useless, unfit, inapplicable)
3
in poor health(expression, adjective, idiom, mean, sick)
3
inadaptable(adjective, useless, unfit, inapplicable)
3
inane(adjective, absurd)
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APASmart Define. (2016). invalid thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/invalid/thesaurus/synonyms
ChicagoSmart Define. 2016. "invalid thesaurus" https://smartdefine.org/invalid/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2016, invalid thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/invalid/thesaurus/synonyms>.
MLASmart Define. "invalid thesaurus" 29 March 2016. Web. 20 September 2026. <https://smartdefine.org/invalid/thesaurus/synonyms>