Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

  

English definition of “efficacy”

efficacy

noun [U]     /ˈef.ɪ.kə.si/ formal
an ability , especially of a medicine or a method of achieving something, to produce the intended result : They recently ran a series of tests to measure the efficacy of the drug . → Synonym effectivenessEfficient and effective
(Definition of efficacy noun from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
Focus on the pronunciation of efficacy

Definitions of “efficacy” in other dictionaries

Translations of “efficacy”

Word of the Day

chef

a skilled and trained cook who works in a hotel or restaurant, especially the most important cook

Word of the Day

Blog

Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More