from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Producing or capable of producing a desired effect. See Synonyms at effective.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. effective

from the GNU version of the Collaborative International Dictionary of English

  • adj. Possessing the quality of being effective; productive of, or powerful to produce, the effect intended.

from The Century Dictionary and Cyclopedia

  • Producing the desired effect; having power adequate to the purpose intended; effectual in operation or result.
  • Synonyms Efficient, Effectual, etc. (see effective); active, operative, energetic.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. marked by qualities giving the power to produce an intended effect
  • adj. producing or capable of producing an intended result or having a striking effect


from The American Heritage® Dictionary of the English Language, 4th Edition

From Latin efficāx, efficāc-, from efficere, to effect; see effect.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Old French efficacieux, from Latin efficax ("efficacious"), from efficere ("to effect, accomplish, to"); see effect.


  • The special grace which we refer to as efficacious is sometimes called irresistible grace.

    The Reformed Doctrine of Predestination

  • Those, however, which follow the last judgment, are simply and absolutely called efficacious volition and nolition, to which the effect succeeds.

    The Works of James Arminius, Vol. 2

  • 'efficacious' - despite the fact that the chemist sells the medicines.

    Home | Mail Online

  • How many songs do you know that use the word "efficacious" without missing a beat?

    Archive 2009-03-01

  • Time is not by itself "efficacious"; that is, the mere passage of time does not augment or diminish the capacities of anything and, in particular, it does not enhance or decrease an agent's powers or abilities.


  • The term “apotropaic” is a broad term referring to something intended to ward off evil, whereas the word “magic” in this case, simply refers to any ritualized behavior believed by its practitioners to be efficacious, that is, effective. [

    RCIA Presentation: The Old Testament

  • Company manager Jong Song Ho, 38, told KCNA that the drink was particularly "efficacious" among workers at a thermal power station, smelter and at medical institutions.

    Reuters: Top News

  • Framingham-based GTC Biotherapeutics 'ATryn, an anti-clotting medicine made from the milk of genetically altered goats, was deemed safe and "efficacious" by an FDA advisory panel.

    Business -

  • The CIA's own Inspector General wrote that waterboarding was not "efficacious" in producing information

    Propeller Most Popular Stories

  • Army Reserve strategic intelligence officer who taught prisoner interrogation and military law for 18 years with the Sixth Army Intelligence School wrote that waterboarding was not "efficacious" in producing information

    Alex Jones' Prison


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  • Lily The Pink!!

    '... the saviour of the human race

    for she invented medicinal compound

    most efficacious .....'

    March 2, 2008