Meanings
adjectiveinefficacious (comparative more inefficacious, superlative most inefficacious)
comparative more inefficacious · superlative most inefficacious
- Incapable of having the intended consequence.
- Not effective.
Synonyms & antonyms
Similar
adjectivelacking the power to produce a desired effect
Opposite
Synonym sets from Open English WordNet, CC BY 4.0.
Origin
- Proto-Indo-European*né
- Proto-Indo-European*n̥-
- Proto-Italic*n̥-
- Latinin-
- Middle Englishin-
- Englishin-
- Proto-Indo-European*h₁éǵʰ
- Proto-Indo-European*h₁éǵʰs
- Proto-Italic*eks
- Latinex
- Latinex-
- Proto-Indo-European*dʰeh₁-
- Proto-Indo-European*dʰeh₁k-
- Proto-Indo-European*dʰh₁kyéti
- Proto-Italic*θakjō
- Proto-Italic*fakjō
- Latinfaciō
- Latinefficiō
- Latinefficāx
- Proto-Indo-European*h₃ed-
- Proto-Indo-European*h₃édosder.?
- Old Frenchefficacieux
- Englishefficacious
- Englishinefficacious
From in- + efficacious.
Full word history & related roots →Translations
Bulgarian неефективен, неефикасен
- неефективен (neefektiven)Incapable of having the intended consequence
- неефикасен (neefikasen)Incapable of having the intended consequence
Rhymes & wordplay
Rhymes with inefficacious
spacioustenaciousgraciousgaseouscretaceousherbaceousaudaciousefficaciousvoraciousvivaciousfallaciouscarbonaceoussebaceousvexatiousflirtatiouscurvaceousostentatioussalaciousrapaciouscapacioussagaciouspugnaciousloquaciousmendacious
All rhymes →Cite this entry
APA
inefficacious. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/inefficacious
MLA
“inefficacious.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/inefficacious. Accessed November 2, 2026.
Chicago
WatkinsX Dictionary, s.v. “inefficacious,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/inefficacious.
Source: inefficacious on Wiktionary, CC BY-SA 4.0.