Try Our Apps


Avoid these words. Seriously.


[ef-i-key-shuh s] /ˌɛf ɪˈkeɪ ʃəs/
capable of having the desired result or effect; effective as a means, measure, remedy, etc.:
The medicine is efficacious in stopping a cough.
Origin of efficacious
1520-30; < Latin efficāci- (stem of efficāx) effectual. See efficient, -acious
Related forms
efficaciously, adverb
efficaciousness, noun
nonefficacious, adjective
nonefficaciously, adverb
unefficacious, adjective
unefficaciously, adverb Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
Cite This Source
Examples from the Web for efficaciously
Historical Examples
  • Only one here can tell him efficaciously what he must hear, and that is Cayrol.

    Serge Panine, Complete Georges Ohnet
  • Yet small as are the variations, they act most efficaciously on certain minds.

  • He learns to manage his genius more prudently and efficaciously.

    Biographia Literaria Samuel Taylor Coleridge
  • Any generation that wants to can do well, but it must want to do efficaciously.

  • This I hinted to L——, and his own susceptibility had hinted it to him efficaciously before I spoke.

    Leonora Maria Edgeworth
  • Nothing has contributed so efficaciously, for some years past, to the progress of the native English drama.

    The English Stage Augustin Filon
  • Ivan felt but little inconvenience from his wound; the aged Hagar having treated it so efficaciously.

    The Circassian Chief W.H.G. Kingston
  • We have not been able to preserve them efficaciously for the future, or to ruminate over them again and again.

  • All the sartorial ingenuity of mankind has not yet succeeded in sewing an apron that will efficaciously hide our sense of shame.

  • It covertly but most efficaciously undermined the customs which it pretended merely to interpret.

    Ancient Law Sir Henry James Sumner Maine
British Dictionary definitions for efficaciously


capable of or successful in producing an intended result; effective as a means, remedy, etc
Derived Forms
efficaciously, adverb
efficaciousness, noun
Word Origin
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
Cite This Source
Word Origin and History for efficaciously



"sure to have the desired effect" (often of medicines), 1520s, from Latin efficaci-, stem of efficax (see efficacy) + -ous. Related: Efficaciously; efficaciousness.

Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source

Word of the Day

Nearby words for efficaciously

Word Value for efficaciously

Scrabble Words With Friends