efficacy

American  

[ef-i-kuh-see] / ˈɛf ɪ kə si /

Sometimes efficacity

noun

plural

efficacies

1. the capacity for producing a desired result or effect.

   Short, frequent periods of practice were shown to have greater efficacy than longer and less frequent ones.

2. a measure of the success of a vaccine or other pharmaceutical when used in the controlled environment of a clinical trial, as opposed to in the real world.

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efficacy British  

/ ˈɛfɪkəsɪ /

noun

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

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Other Word Forms

• nonefficacy noun

Etymology

Origin of efficacy

First recorded in 1520–30; from Latin efficācia, from efficāc- (stem of efficāx ) “effective, effectual” + -ia, noun suffix; efficacious ( def. ), -y ³ ( def. )

Example Sentences

And questions remain around the efficacy of removal programs and credits.

From The Wall Street Journal

"Some of the SPF testing, I feel, has become a bit more of a marketing exercise than a real reflection of efficacy," cosmetic chemist Michelle Wong told the BBC last year.

From BBC

Freymann, a fellow at Stanford University’s Hoover Institution, argues that the historical U.S. playbook for the Asia-Pacific is losing its efficacy.

From The Wall Street Journal

The biotech company released positive data for a Phase 2 study evaluating the efficacy of zumilokibart, a monoclonal antibody targeting proteins related to inflammation, in patients with atopic dermatitis.

From Barron's

Pfizer continued to express confidence in its experimental Lyme vaccine’s potential, noting that the study hit a different statistical measure and the vaccine showed “clinically meaningful efficacy.”

From The Wall Street Journal

Related Words

• adequacy
• competence
• effectiveness
• potency
• virtue