# efficacious

> English word · Adjective · IPA /ˌɛf.ɪˈkeɪ.ʃəs/ · frequency rank #49,890

## Definitions
1. Effective; possessing efficacy.

## Etymology
From Old French efficacieux, from Latin efficāx (“efficacious”) + -ous, from efficere (“to effect, to accomplish”); see effect.

## Common misspellings (13)
`effciacious`, `effiaccious`, `efficaccious`, `efficaciosu`, `efficaciouss`, `efficaciuos`, `efficacoius`, `efficaicous`, `efficcacious`, `efficcaious`, `eficacious`, `efifcacious`, `feficacious`

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/efficacious