Dictionary.com

efficacious

[ ef-i-key-shuhs ]
/ ˌɛf ɪˈkeɪ ʃəs /
Save This Word!
See synonyms for: efficacious / efficaciously / efficaciousness on Thesaurus.com

adjective
capable of having the desired result or effect; effective as a means, measure, remedy, etc.: The medicine is efficacious in stopping a cough.
QUIZ
ARE YOU A TRUE BLUE CHAMPION OF THESE "BLUE" SYNONYMS?
We could talk until we're blue in the face about this quiz on words for the color "blue," but we think you should take the quiz and find out if you're a whiz at these colorful terms.
Question 1 of 8
Which of the following words describes “sky blue”?
Meet Grammar CoachWrite or paste your essay, email, or story into Grammar Coach and get grammar helpImprove Your Writing
Meet Grammar CoachImprove Your Writing
Write or paste your essay, email, or story into Grammar Coach and get grammar help

Origin of efficacious

First recorded in 1520–30; from Latin efficāci- (stem of efficax ) “effectual.” See efficient, -acious

OTHER WORDS FROM efficacious

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

How to use efficacious in a sentence

British Dictionary definitions for efficacious

efficacious
/ (ˌɛfɪˈkeɪʃəs) /

adjective
capable of or successful in producing an intended result; effective as a means, remedy, etc

Derived forms of efficacious

efficaciously, adverbefficaciousness, noun

Word Origin for efficacious

C16: from Latin efficāx powerful, efficient, from efficere to achieve; see effect
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
FEEDBACK