Synonyms|215Antonyms|56|Broader|0Narrower|0Related|93
3
sterile
2
failing
2
hopeless(adjective, useless, vain, ineffective, unsuccessful)
2
inferior(adjective, inadequate, limited, feeble, useless)
2
innocuous(adjective, inferior, inadequate, limited, feeble)
2
limited(adjective, inferior, inadequate, feeble, useless)
2
meaningless
2
unfortunate
2
unrewarding(adjective, arouse bad feelings)
2
unskillful(incompetent, wasteful, unproductive, inutility)
2
void(adjective, inferior, inadequate, useless, trivial)
2
weak(skill, incompetent, unfit, inept, powerless)
1
abstract(wild, unreasonable, useless, absurd, unrealistic)
1
absurd(wild, unreasonable, useless, unrealistic, unattainable)
1
anticlimactic(adjective, inferior, inadequate, limited, feeble)
1
chimerical(wild, unreasonable, useless, absurd, abstract)
1
clumsy(weak, skill, inadequate, unfit, inept)
1
defeasible(adjective, inferior, inadequate, limited, feeble)
1
dispensable
1
effete
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ChicagoSmart Define. 2016. "inefficacious thesaurus" https://smartdefine.org/inefficacious/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, inefficacious thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/inefficacious/thesaurus/synonyms>.
MLASmart Define. "inefficacious thesaurus" 24 March 2016. Web. 23 September 2026. <https://smartdefine.org/inefficacious/thesaurus/synonyms>