If you talk about the efficacy of something, you are talking about its effectiveness and its ability to do what it is supposed to.
[formal]
Recent medical studies confirm the efficacy of a healthier lifestyle.
Synonyms: effectiveness, efficiency, power, value More Synonyms of efficacy
efficacy in British English
(ˈɛfɪkəsɪ) or efficaciousness (ˌɛfɪˈkeɪʃəsnəs)
noun
the quality of being successful in producing an intended result; effectiveness
efficacy in American English
(ˈɛfɪkəsi)
noun
power to produce effects or intended results; effectiveness
Word origin
ME & OFr efficace < L efficacia < efficax: see efficacious
Examples of 'efficacy' in a sentence
efficacy
Their role is to assess the safety and efficacy of new treatments.
Times, Sunday Times (2008)
The next round of trials will delve further into the efficacy of the treatment.
Times, Sunday Times (2014)
Phase two tests the efficacy of a treatment.
Times, Sunday Times (2008)
It will allow doctors to measure the progress of the disease and the efficacy of treatments.
Times, Sunday Times (2006)
This incident shows the efficacy of ejection seats.
Times, Sunday Times (2009)
It also questioned the efficacy of retention bonuses.
Times, Sunday Times (2010)
But questions about its efficacy are no surprise.
Times, Sunday Times (2011)
This riot of manifesto pledges then calls into question the very efficacy of politics as an agent of change.
Times, Sunday Times (2015)
In the case of a medicine this includes all the safety and efficacy tests required before it can be introduced to clinical practice.
Times, Sunday Times (2011)
As with any new technology, rigorous testing for both safety and efficacy is of course essential.
Times, Sunday Times (2015)
The first stages of a clinical trial are to prove the safety, the quality and the efficacy of a drug.
Times, Sunday Times (2006)
The efficacy of a treatment is not within the judgement of the CQC.
Times, Sunday Times (2012)
While the study could assess the treatment 's efficacy, it was not big enough to assess its risk.
Times, Sunday Times (2016)
Regulators had concluded there were no major quality, safety or efficacy issues to be resolved, the company said.
Times, Sunday Times (2010)
If it is a cosmetic and not an over-the-counter drug, it has not received approval for safety and efficacy.
Brumberg, Elaine Take Care of Your Skin (1990)
The rejection of cannabis preparations for the release of spasms experienced by patients with MS is on the grounds that its efficacy is not proven in trials.
Times, Sunday Times (2006)
In other languages
efficacy
British English: efficacy NOUN
If you talk about the efficacy of something, you are talking about its effectiveness and its ability to do what it is supposed to.
Recent medical studies confirm the efficacy of a healthier lifestyle.
American English: efficacy
Brazilian Portuguese: eficácia
Chinese: 功效
European Spanish: eficacia
French: efficacité
German: Wirksamkeit
Italian: efficacia
Japanese: 有効性
Korean: 실효성
European Portuguese: eficácia
Latin American Spanish: eficacia
(noun)
Recent medical studies confirm the efficacy of a healthier lifestyle.
Synonyms
effectiveness
the effectiveness of computers as an educational tool
efficiency
ways to increase agricultural efficiency
power
He had no power in his left arm.
value
Studies are needed to see if these therapies have any value.
success
strength
maximum-strength migraine tablets
virtue
There is no virtue in overexercising.
vigour
He lacks the vigour of a normal, healthy teenager.
He played with great vigour.
use
There's no use you asking me any more questions about that.
usefulness
His interest lay in the usefulness of his work.
potency
The potency of the flavours increases with time.
fruitfulness
productiveness
efficaciousness
Additional synonyms
in the sense of efficiency
ways to increase agricultural efficiency
Synonyms
effectiveness,
power,
economy,
productivity,
organization,
efficacy,
cost-effectiveness,
orderliness
in the sense of potency
The potency of the flavours increases with time.
Synonyms
power,
force,
strength,
effectiveness,
efficacy
in the sense of power
Definition
political, financial, or social force or authority