efficacy

Everyday

(formal) The power to produce the result you want, especially of a medicine, treatment or method. tree →

In the lessons

A formal word used in science and medicine, and in exam texts. Scientists measure the efficacy of medicines in careful trials. Phrases: «the efficacy of», «proven efficacy», «test the efficacy».

Examples

• Doctors tested the efficacy of the new vaccine. tree →
• We doubted the efficacy of his homemade cure. tree →
• The efficacy of the method was shown by better test results. tree →
• Studies prove the efficacy of hand washing against germs. tree →
• Scientists compared the efficacy of two sun creams. tree →
• The efficacy of prayer is a matter of faith for many. tree →
• This he readily accepted, trusting to the efficacy of the antidote. tree →

Note

Uncountable, formal. Adjective: «efficacious». Do not confuse with «efficiency» (doing something without waste of time or energy). Stress: EF-ih-kuh-see.