5
weak(adjective, skill, well, incompetent, unqualified)
4
abortive(failure, inferior, inadequate, limited, feeble)
4
bootless(failure, inferior, inadequate, limited, feeble)
4
dysfunctional(useless, unadaptive)
4
inconsequential
4
slovenly(adjective, well, incompetent, wasteful, unproductive)
4
unapt(useless, incompetent, unqualified, inept, clumsy)
4
uneffective
4
unfitted(weak, inadequate, useless, unqualified, unable)
4
unprepared(adjective, well, incompetent, unqualified, inept)
4
unsatisfactory(adjective, weak, feeble, ineffective, inexpedient)
4
unskilful
4
unworkmanlike(adjective, ability)
3
feckless(inferior, inadequate, limited, feeble, useless)
3
fruitless(adjective, weak, failure, inferior, inadequate)
3
inoperative(weak, skill, inferior, inadequate, feeble)
3
lame(adjective, weak, thin, delicate, inferior)
3
powerless(adjective, weak, thin, delicate, inferior)
3
slack(adjective, well, dubious, incompetent, lazy)
3
sloppy(adjective, well, incompetent, wasteful, unproductive)
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APASmart Define. (2015). inefficient thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/inefficient/thesaurus/synonyms
ChicagoSmart Define. 2015. "inefficient thesaurus" https://smartdefine.org/inefficient/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, inefficient thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/inefficient/thesaurus/synonyms>.
MLASmart Define. "inefficient thesaurus" 12 November 2015. Web. 22 September 2026. <https://smartdefine.org/inefficient/thesaurus/synonyms>