Efficacious and Uneffective

Opposite meaning words

Efficacious adjective - Marked by qualities giving the power to produce an intended effect.

Usage example: "written propaganda is less efficacious than the habits and prejudices...of the readers"-Aldous Huxley

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Uneffective is an antonym for efficacious.

Uneffective adjective - Not producing an intended effect.

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Efficacious is an antonym for uneffective.

Cite this Source

Uneffective and Efficacious. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/efficacious/uneffective

Efficacious & Uneffective. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/efficacious/uneffective>.

Uneffective or Efficacious. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/efficacious/uneffective.

Google Ngram Viewer shows how "efficacious" and "uneffective" have occurred on timeline