Synonyms|412Antonyms|83|Broader|4Narrower|1Related|376
1
clumsy
1
conceptual
1
counterproductive
1
defective
1
deficient
1
derelict
1
derisory
1
enervated
1
fallow
1
faulty
1
feckless
1
flimsy
1
grievous
1
impotent(adjective, weak)
1
in vain
1
incompetent
1
inexpert
1
lazy
1
non-beneficial(adjective, effect, result, outcome)
1
unavailing
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APASmart Define. (2015). efficacious thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/efficacious/thesaurus/antonyms
ChicagoSmart Define. 2015. "efficacious thesaurus" https://smartdefine.org/efficacious/thesaurus/antonyms (accessed September 23, 2026).
HarvardSmart Define 2015, efficacious thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/efficacious/thesaurus/antonyms>.
MLASmart Define. "efficacious thesaurus" 13 October 2015. Web. 23 September 2026. <https://smartdefine.org/efficacious/thesaurus/antonyms>