Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “efficacy”

efficacy

noun [U] uk   /ˈef.ɪ.kə.si/ formal us  
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
(Definition of efficacy from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of efficacy?
Add Cambridge dictionaries to your browser to your website

Definitions of “efficacy” in other dictionaries

Translations of “efficacy”

Word of the Day

hello stranger

said to a person that you know but have not seen for a long time

Word of the Day

Come on – you can do it! Phrasal verbs with ‘come’.

by Liz Walter​,
November 19, 2014
As part of an occasional series on the tricky subject of phrasal verbs, this blog looks at ones formed with the verb ‘come’. If you are reading this blog, I’m sure you already know come from, as it is one of the first things you learn in class: I come from Scotland/Spain.

Read More 

silver splicer noun

November 17, 2014
informal a person who marries in later life Newly retired and now newlywed – rise of the ‘silver splicers’ Reaching pension age becomes a trigger to tie the knot as baby-boomers begin to redefine retirement

Read More