Efficient and Inefficacious
Opposite meaning words
Efficient
Efficient adjective - Producing or capable of producing a desired result.
Inefficacious is an antonym for efficient.
Inefficacious
Inefficacious adjective - Not producing the desired result.
Usage example: his efforts to restore the neglected houseplant back to health were belated and sadly inefficacious
Efficient is an antonym for inefficacious.
Cite this Source
Inefficacious and Efficient. (2016). Retrieved 2026, August 15, from https://thesaurus.plus/related/efficient/inefficacious
Efficient & Inefficacious. N.p., 2016. Web. 15 Aug. 2026. <https://thesaurus.plus/related/efficient/inefficacious>.
Inefficacious or Efficient. 2016. Accessed August 15, 2026. https://thesaurus.plus/related/efficient/inefficacious.
Google Ngram Viewer shows how "efficient" and "inefficacious" have occurred on timeline