efficacious [ef-i-key -shuh s]
Word Origin
capable of having the desired result or effect; effective as a means, measure, remedy, etc.: The medicine is efficacious in stopping a cough. Show More
Origin of efficacious 1520–30; <
Latin efficāci- (stem of
efficāx ) effectual. See
efficient ,
-acious Related forms ef·fi·ca·cious·ly , adverb ef·fi·ca·cious·ness , noun non·ef·fi·ca·cious , adjective non·ef·fi·ca·cious·ly , adverb un·ef·fi·ca·cious , adjective un·ef·fi·ca·cious·ly , adverb Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for non-efficacious capable of or successful in producing an intended result; effective as a means, remedy, etc Show More
Derived Forms efficaciously , adverb efficaciousness , 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
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Word Origin and History for non-efficacious adj. "sure to have the desired effect" (often of medicines), 1520s, from Latin efficaci- , stem of efficax (see efficacy ) + -ous . Related: Efficaciously ; efficaciousness .
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Online Etymology Dictionary, © 2010 Douglas Harper
