7
unskillful(adjective, ability, inadequate, useless, well)
6
careless(adjective, well, extravagant, incompetent, lavish)
6
extravagant(adjective, well, incompetent, lavish, wasteful)
6
helpless(adjective, weak, thin, delicate, inadequate)
6
inapt(adjective, ability, impotence)
6
slipshod(adjective, well, incompetent, wasteful, unproductive)
6
time-consuming
6
unprofessional(adjective, immoral, unprincipled, unethical, skillfully)
6
unprofitable(adjective, inferior, inadequate, limited, feeble)
6
worthless(adjective, inferior, inadequate, limited, feeble)
5
awkward(adjective, inadequate, useless, incompetent, unqualified)
5
clumsy(adjective, weak, inadequate, useless, incompetent)
5
disorganized(adjective, well, incompetent, inept, wasteful)
5
faulty(adjective, weak, feeble, well, incompetent)
5
improvident(adjective, well, extravagant, incompetent, lavish)
5
insufficient(adjective, weak, thin, delicate, failure)
5
mediocre
5
poor(adjective, weak, thin, delicate, feeble)
5
untrained(adjective, inadequate, useless, well, incompetent)
5
wasteful(adjective, slow, extravagant, incompetent, lavish)
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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>