EFFICACIOUS Antonyms

There are 11 antonyms of the word efficacious. (opposite meanings)

Did you mean?
Definition of EFFICACIOUSSynonyms of EFFICACIOUS

Also try opposite words for..
efficacy efficaciously

Best Opposite Words For EFFICACIOUS


Expand?	Word	Save?	Synonyms..	Usage	Type
	feeble				adjectiveadj
	adjective satellite • pathetically lacking in force or effectiveness • lacking strength or vigor • lacking bodily or muscular strength or vitality • lacking strength
	fruitless				verb, adjectivev, adj
	adjective satellite • unproductive of success
	impotent				adjectiveadj
	adjective • lacking power or ability • (of a male) unable to copulate
	ineffective				adjectiveadj
	adjective • not producing an intended effect adjective satellite • lacking in power or forcefulness • lacking the ability or skill to perform effectively; inadequate
	inefficient				adjectiveadj
	adjective • not producing desired results; wasteful adjective satellite • lacking the ability or skill to perform effectively; inadequate
	powerless				adjectiveadj
	adjective • lacking power
	unproductive				adjectiveadj
	adjective • not producing or capable of producing adjective satellite • not producing desired results
	unsuccessful				adjectiveadj
	adjective • not successful; having failed or having an unfavorable outcome adjective satellite • failing to accomplish an intended result
	useless				adjectiveadj
	adjective • having no beneficial use or incapable of functioning usefully
	weak				adjectiveadj
	adjective • wanting in physical strength adjective satellite • overly diluted; thin and insipid • (used of vowels or syllables) pronounced with little or no stress • wanting in moral strength, courage, or will; having the attributes of man as opposed to e.g. divine beings • tending downward in price • deficient or lacking in some skill • lacking bodily or muscular strength or vitality • (used of verbs) having standard (or regular) inflection • not having authority, political strength, or governing power • deficient in magnitude; barely perceptible; lacking clarity or brightness or loudness etc • likely to fail under stress or pressure • deficient in intelligence or mental power
	inefficacious				adjectiveadj
	adjective • lacking the power to produce a desired effect