adjective ef·fi·ca·cious \ˌe-fə-ˈkā-shəs\

: having the power to produce a desired result or effect

Full Definition of EFFICACIOUS

:  having the power to produce a desired effect <an efficacious remedy>
ef·fi·ca·cious·ly adverb
ef·fi·ca·cious·ness noun


  1. <taking a cookie break while studying is one of the most efficacious ways of rejuvenating the mind that I have ever discovered>


Latin efficac-, efficax, from efficere
First Known Use: 1528

Synonym Discussion of EFFICACIOUS

effective, effectual, efficient, efficacious mean producing or capable of producing a result. effective stresses the actual production of or the power to produce an effect <an effective rebuttal>. effectual suggests the accomplishment of a desired result especially as viewed after the fact <the measures to stop the pilfering proved effectual>. efficient suggests an acting or a potential for action or use in such a way as to avoid loss or waste of energy in effecting, producing, or functioning <an efficient small car>. efficacious suggests possession of a special quality or virtue that gives effective power <a detergent that is efficacious in removing grease>.


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