What is the opposite of efficacious?

Need antonyms for efficacious? Here's a list of opposite words from our thesaurus that you can use instead.

Contexts ▼▲ (of something inanimate or abstract) Opposite of successful in producing a desired or intended result Opposite of reasonable and convincing Opposite of good and important enough to spend time, effort, or money on Opposite of of a suitable quality, standard, or type to meet the required purpose Opposite of denotes the effectiveness or dominance of a particular action Opposite of having great impact or influence Opposite of incapable of going wrong or being misused Opposite of always successful, not likely to fail Opposite of appropriate or suitable in the circumstances Opposite of convincing or compelling in nature Opposite of based on, or displaying, common sense Opposite of having, showing, or done with good judgment or sense Opposite of present as the strongest or main element Opposite of being in effective or current operation, action, or force Opposite of made or adjusted to be as efficient as possible … more ▼ ▲ Adjective ▲ (of something inanimate or abstract) Opposite of successful in producing a desired or intended result unproductive useless ineffective inefficacious ineffectual unsuccessful fruitless futile inefficient inoperative unfruitful abortive impotent incapable unavailing weak vain worthless pointless unprofitable profitless bootless empty inadequate idle hopeless otiose poor barren failed nugatory purposeless inferior feeble pathetic inept incompetent feckless lame counterproductive paltry inutile inexpedient powerless null hamstrung unfructuous limited anticlimactic unable unfit void indecisive non-successful to no effect to no avail helpless unmoving unimpressive hollow unrewarding impactless unpoignant unstirring unstimulating uninspirational unconvincing implausible uninfluential untouching forceless unpersuasive questionable inconclusive insignificant flimsy unbelievable suspect defeated thwarted luckless foiled ill-fated unprosperous doomed bad uneconomic losing depressed forfeiting more ❯ Adjective ▲ Opposite of reasonable and convincing unconvincing inconclusive indecisive ineffective uncompelling unpersuasive impotent invalid muddled unimportant vague weak feeble implausible unimpressive ineffectual flimsy incredible unbelievable improbable inadequate unsuccessful meek incapable dissuasive shallow lame poor questionable unsatisfactory suspect inconceivable unlikely inept incompetent insipid indefinite incoherent unintelligent stupid wanting ignorant obscure irrelevant faulty unfounded substandard unsubstantial immaterial deficient lacking inconsequential incomplete shaky half-hearted groundless hollow raw pathetic untrained unqualified unsure imperfect forceless inapt failing impactless defective insufficient flabby limited unremarkable toothless disputable immature lousy understated derisory laughable unpronounced unprepared rambling inactive gentle moderate mild lethargic apathetic idle unforceful passive vain dubious specious fanciful unconceivable disheartening dampening discouraging unreasonable illogical unthinkable doubtful unrealistic trifling incredulous unsound thin fantastical unimaginable not convincing beyond belief far-fetched scarcely credible not credible difficult to believe hard to believe more ❯ Adjective ▲ Opposite of good and important enough to spend time, effort, or money on useless worthless unimportant pointless trivial unworthy vain valueless bad disadvantageous hurting inconsequential unhelpful unprofitable wasteful fruitless ineffectual unproductive inefficient futile ineffective unfavorableUS unfavourableUK inoperative impotent unfruitful negative stupid unpurposed feckless unworkable unserviceable meaningless inept inadequate dysfunctional unusuable pathetic unavailing incompetent unsuccessful nonfunctional weak unusable purposeless impracticable profitless unfunctional unuseful good-for-nothing unskilled abortive hopeless nonproductive empty uncreative slow sterile lazy unyieldly barren impractical nongood harmful detrimental doubtful more ❯ Adjective ▲ Opposite of of a suitable quality, standard, or type to meet the required purpose impracticable impractical inapplicable inoperable nonfunctional nonpractical unavailable unemployable unusable unworkable useless disadvantageous unfavorableUS unfavourableUK bad prohibitive disagreeable detrimental harmful hurtful injurious unprofitable profitless unhelpful troublesome deleterious objectionable inopportune inconvenient prejudicial untimely adverse obstructive undesirable bothersome ineffective inadequate impotent ineffectual incapable invalid unsuccessful inexpedient unsuitable nonproductive inept fruitless futile inoperative worthless feckless inactive substandard weak inutile defective counterproductive not effective unpurposed incongruous imperfect unserviceable inapt of no use dysfunctional uncongenial fallible fail expendable unpropitious unbeneficial unfitting incompatible unwise scrap unfruitful unuseful destructive theoretical erring improper bootless inappropriate infelicitous waste unworthwhile not useful inefficacious unavailing malapropos faultful purposeless inapposite unfunctional valueless good-for-nothing abortive no good hopeless unbefitting more ❯ Adjective ▲ Opposite of denotes the effectiveness or dominance of a particular action ineffective ineffectual lethargic incapable inefficacious lacklusterUS lacklustreUK useless apathetic dilatory dormant draggy dull exhausted indifferent indolent inert laggard languorous lazy listless passive somnolent spiritless unmoving without energy inactive idle unable “Leaders who do not look after the interests of their followers are not only unethical but ineffective.” Adjective ▲ Opposite of having great impact or influence uninfluential insignificant inconsequential infinitesimal irrelevant trivial pointless trifling immaterial inconsiderable meagreUK meagerUS meaningless paltry petty purportless anonymous casual feeble flimsy frail helpless inappreciable incompetent inept inexpert infirm minimal nameless obscure senseless uncelebrated unfit unknown unqualified unskilled unskillful light lightweight little nonessential nugatory slight small unsubstantial nondescript unimportant faint languid low muffled quiet soft unimpressive “We would end up an impotent and uninfluential nation, just one voice among the many.” Adjective ▲ Opposite of incapable of going wrong or being misused flawed risky fallible erratic unstable unreliable undependable iffy inconclusive equivocal ambiguous speculative questionable error-prone untrustworthy unpredictable errable uncertain errant doubting indefinite unconfident undecided Adjective ▲ Opposite of always successful, not likely to fail fallible doubtful dubious error-prone uncertain undependable unreliable unsure defective erring faultful faulty imperfect Adjective ▲ Opposite of appropriate or suitable in the circumstances inappropriate improper inapplicable inapposite infelicitous unsuitable inapt incongruous indecent malapropos misbecoming unapt unbecoming unbeseeming unfit unfitting unhappy unmeet unseemly wrong ill-fitted ill-suited ill-timed inopportune irrelevant untimely disinclined incapable incorrect stupid unskilled Adjective ▲ Opposite of convincing or compelling in nature nonaggressive peaceful weak Adjective ▲ Opposite of based on, or displaying, common sense groundless baseless unjustified Unsupported unfounded unsubstantiated unwarranted illogical nonsensical unreasoned fallacious foundationless incoherent unjustifiable inconsequential questionable sham untrue bogus specious unrecognisedUK unrecognizedUS weak erroneous invalid unrealistic wrong illegitimate spurious untrustworthy false inconsequent misguided unreliable gratuitous imaginary nonrational unconvincing unsound causeless illusory uninformed unproven unreasonable irrational nonvalid uncorroborated unsupported ill-founded uncalled for uncalled-for without basis without cause without explanation without foundation without justification without reason not backed up “Of course, the moment I got there it was clear that all my concerns were completely groundless.” Adjective ▲ Opposite of having, showing, or done with good judgment or sense foolish imprudent silly unwise irrational stupid thoughtless idiotic rash reckless careless dumb inane outrageous simpleminded unsound farcical featherheaded hasty ignorant mindless trivial doltish frivolous heedless inept senseless asinine inconsiderable indiscreet nonsensical thickheaded unintelligent fatuous foolhardy imbecilic inconsequential inexpedient unreasonable dippy feebleminded gormless harebrained implausible injudicious uncareful unimportant daft illogical inadvisable lunkheaded ridiculous tomfool trifling unrealistic absurd dim fanciful impolitic incautious insignificant witless brainless inattentive irresponsible preposterous simple tactless worthless dim-witted half-baked half-witted ill-advised ill-considered ill-judged short-sighted weak-minded wasteful inefficient improvident “His ideas are obviously foolish, easily disproved, an affront to any reasoning person.” Adjective ▲ Opposite of present as the strongest or main element minor last least inferior secondary subordinate subsidiary unimportant uninfluential inconsequential trivial Adjective ▲ Opposite of being in effective or current operation, action, or force inoperative dormant inactive broken deactivated dead decommissioned defective ineffective ineffectual inefficacious inert inoperable kaput kaputt nonactivated nonactive nonfunctional non-functional nonfunctioning nonoperating nonoperational nonoperative unserviceable unusable unworkable useless abeyant disinterested quiet unmovable “The rides have become inoperative since its closure in the early 2000s.” Adjective ▲ Opposite of made or adjusted to be as efficient as possible unoptimized disorganisedUK disorganizedUS inefficacious inefficient uneconomical unproductive wasteful Find more words! 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Sentences with the word efficacious Words that rhyme with efficacious What is the adverb for efficacious? What is the adjective for efficacious? What is the noun for efficacious? Translations for efficacious Use our Antonym Finder Nearby Words efficaciously efficaciousness efficacities efficacity efficacy efficiencies efficacies effeteness effetely effete effervescently effervescent 11-letter Words Starting With e ef eff effi effic effica efficac efficaci efficacio efficaciou