Definitions

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

  • adj. Not capable of producing a desired effect or result; ineffective.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Incapable of having the intended consequence.
  • adj. Not effective.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Not efficacious; not having power to produce the effect desired; inadequate; incompetent; inefficient; impotent.

from The Century Dictionary and Cyclopedia

  • Not efficacious; not having power to produce the effect desired; of inadequate force.

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

  • adj. lacking the power to produce a desired effect

Etymologies

Sorry, no etymologies found.

Examples

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Comments

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  • He also used on the Daily Show last night, I think.

    Take efficacy, add some affixes, and bingo, you have a word hardly any can understand.

    September 21, 2007

  • inefficacious on National Public radio today (thursday, 20 September 2007).

    September 20, 2007