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efficacious

[ef-i-key-shuh s] /ˌɛf ɪˈkeɪ ʃəs/
adjective
1.
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
1520-1530
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
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2016.
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British Dictionary definitions for non-efficacious

efficacious

/ˌɛfɪˈkeɪʃəs/
adjective
1.
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
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Word Origin and History for non-efficacious

efficacious

adj.

"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
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