efficacy

[ ef-i-kuh-see ]

noun

, plural ef·fi·ca·cies.

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. Compare effectiveness ( def 3 ).

efficacy

/ ˈɛfɪkəsɪ /

noun

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

Other Words From

• non·ef·fi·ca·cy noun

Word History and Origins

Origin of efficacy¹

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

Shortly following the Phase 1 trial, a Phase 2a trial will be conducted to further establish the safety and begin to define the efficacy of EV25.

From Science Daily

With the new machine learning methodology, we can now extend our work to investigate how drug-carrying nanoparticles interact with blood proteins and how those interactions change the efficacy of the drug carriers, Häkkinen concludes.

From Science Daily

To validate the efficacy of these reprogrammed cells, they were injected into a developing mouse embryo.

From Science Daily

Most of our body tissues have evolved to regenerate ruptures or fractures with remarkable efficacy, as long as these are small in size.

From Science Daily

Benjamin pointed to Kennedy's previous comments questioning the safety and efficacy of vaccines, and what might happen if there were another pandemic during his tenure.

From BBC

Related Words

• adequacy
• competence
• effectiveness
• potency
• virtue