The definition of efficacious is someone or something that successfully produced a result that was desired.adjective
An example of efficacious is a program that was designed to help stop crime and that reduced the crime rate by 80 percent.YourDictionary definition and usage example. Copyright © 2013 by LoveToKnow Corp.
Origin: L efficax (gen. efficacis) < efficere, to bring to pass, accomplish (see effect) + -ous
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Origin: From Latin efficāx, efficāc-, from efficere, to effect; see effect.
- efˌfi·caˈcious·ly adverb
- efˌfi·caˈcious·ness noun