Synonyms|428Antonyms|78|Broader|9Narrower|13Related|102

26 entries under noun topic. ×

5
inefficacy
3
failure
3
inefficiency
3
weakness
1
inadequacy
1
incompetence
1
ineffectuality
1
ineffectualness
1
stupidity
1
uselessness
0
ineffectiveness
0
clumsiness
0
emptiness
0
enervation(inadequacy, ineffectiveness)
0
frivolity
0
frothiness
0
fruitlessness
0
futility
0
hollowness
0
hopelessness
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APASmart Define. (2015). efficacy thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/efficacy/thesaurus/antonyms
ChicagoSmart Define. 2015. "efficacy thesaurus" https://smartdefine.org/efficacy/thesaurus/antonyms (accessed September 27, 2026).
HarvardSmart Define 2015, efficacy thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/efficacy/thesaurus/antonyms>.
MLASmart Define. "efficacy thesaurus" 10 April 2015. Web. 27 September 2026. <https://smartdefine.org/efficacy/thesaurus/antonyms>