56 entries under adjective topic. ×

24
inefficient(weak, sound, delicate, well)
14
incompetent(strong, weak, delicate, qualified)
8
abortive
7
ineffective(strong, weak, fit, delicate)
6
helpless
4
fruitless
3
impotent
3
ineffectual
2
feckless
2
powerless
1
empty
1
unavailing
1
useless
1
vain
1
wasteful
1
weak
1
worthless
1
non-beneficial(effect, result, outcome)
0
futile
0
disordered
<123>
11 years ago|3.9k views|share |citing 
APASmart Define. (2015). efficient thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/efficient/thesaurus/antonyms
ChicagoSmart Define. 2015. "efficient thesaurus" https://smartdefine.org/efficient/thesaurus/antonyms (accessed September 23, 2026).
HarvardSmart Define 2015, efficient thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/efficient/thesaurus/antonyms>.
MLASmart Define. "efficient thesaurus" 13 April 2015. Web. 23 September 2026. <https://smartdefine.org/efficient/thesaurus/antonyms>