Dictionary Entry
efficacy
nounFind the meaning of the word efficacy, plus dictionary definition, pronunciation, thesaurus-style synonyms, antonyms, and related vocabulary.
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Meaning
Dictionary meaning in a clear, student-friendly format.
the ability of a drug to produce the desired therapeutic effect under ideal conditions in clinical trials
Example Sentence
The new vaccine showed 95% efficacy in preventing illness during the trial.
Usage Note
Use 'efficacy' when discussing how well a medicine, method, or plan works under controlled conditions.