Synonyms|832Antonyms|240|Broader|11Narrower|0Related|915
24
inefficient(adjective, weak, sound, delicate, well)
14
incompetent(adjective, strong, weak, delicate, qualified)
8
abortive(adjective, failing)
7
ineffective(adjective, strong, weak, fit, delicate)
7
not good
6
helpless
5
time-consuming
4
feeble(strong, fit)
4
fruitless
3
impotent
3
ineffectual
2
feckless(adjective, purpose)
2
sinful
2
powerless
2
uneconomical
2
unsuccessful
1
empty
1
unavailing
1
unproductive
1
unprofitable
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APASmart Define. (2015). efficient thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/efficient/thesaurus/antonyms
ChicagoSmart Define. 2015. "efficient thesaurus" https://smartdefine.org/efficient/thesaurus/antonyms (accessed September 22, 2026).
HarvardSmart Define 2015, efficient thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/efficient/thesaurus/antonyms>.
MLASmart Define. "efficient thesaurus" 13 April 2015. Web. 22 September 2026. <https://smartdefine.org/efficient/thesaurus/antonyms>