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efficacy

[ ef-i-kuh-see ]
/ ˈɛf ɪ kə si /
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See synonyms for: efficacy / efficacies on Thesaurus.com

noun, plural ef·fi·ca·cies.
capacity for producing a desired result or effect; effectiveness: a remedy of great efficacy.
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Which of the following nouns has an irregular plural form?
Sometimes ef·fi·cac·i·ty [ef-i-kas-i-tee] /ˌɛf ɪˈkæs ɪ ti/ .

Origin of efficacy

First recorded in 1520–30; from Latin efficācia, equivalent to efficāc- “effective, effectual” + -ia noun suffix; see efficacious, -y3

OTHER WORDS FROM efficacy

non·ef·fi·ca·cy, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

How to use efficacy in a sentence

  • That these two are different will easily be clear to anyone who passes in review their respective efficacies.

  • In silence and secrecy thought has been working, and the benignant efficacies of concealment speak for themselves.

    Ku Klux Klan|J. C. Lester

British Dictionary definitions for efficacy

efficacy
/ (ˈɛfɪkəsɪ) /

noun
the quality of being successful in producing an intended result; effectiveness
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
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