Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Producing or capable of producing a desired effect. synonym: effective.

from The Century Dictionary.

  • 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 the GNU version of the Collaborative International Dictionary of English.

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

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • adjective effective

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

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

Etymologies

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.

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Examples

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

    The Reformed Doctrine of Predestination 1959

  • 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 1560-1609 1956

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

    Home | Mail Online 2010

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

    Home | Mail Online 2010

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

    Home | Mail Online 2010

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

    Archive 2009-03-01 2009

  • 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.

    Fatalism Rice, Hugh 2006

  • 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. [

    Archive 2007-01-01 2007

  • 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 2007

  • 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 2010

Comments

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  • Lily The Pink!!

    '... the saviour of the human race

    for she invented medicinal compound

    most efficacious .....'

    March 2, 2008