Meanings
comparative more efficious · superlative most efficious
- nonstandardrareEfficacious.
[...] was found to be efficious in reducing pain and severity of swelling (Laupattarakasem et al. 1993).
2016, T. K. Lim, Edible Medicinal and Non-Medicinal Plants, volume 122 more examples
Had she not been cured at Oxford, no imputation could have fallen upon me, considering the circumstance of her pregnancy, and the virulence of the symptoms, for which I had used the most efficious remedies in the world.
1770, The Memoirs of Miss Arabella Bolton. Containing a Genuine Account, page 81This remedy will be found speedily efficious in hoarseness due to excessive action of the vocal cords or resulting from an acute cold.
1899, The Carolina Medical Journal, volumes 43-44, page 207, quoting the Medical Standard
Origin
Possibly a variation of efficacious or derivative of efficacy influenced by analysis of the final -c- in the later word as being part of a suffix -cy rather than the word-stem.
Full word history & related roots →Cite this entry
efficious. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/efficious
“efficious.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/efficious. Accessed November 2, 2026.
WatkinsX Dictionary, s.v. “efficious,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/efficious.
Source: efficious on Wiktionary, CC BY-SA 4.0.