Efficacy: meaning, example and synonyms
Efficacyn. The ability to produce the intended or desired result.
Example
Researchers tested the efficacy of the new irrigation method by comparing crop yields from treated and untreated fields over two seasons.
- Part of speech
- noun
- Synonyms
- effectiveness, potency, success, usefulness
- Antonyms
- ineffectiveness, inefficacy, futility, uselessness
- Memory tip
- Efficacy shares a root with effect: does it have the effect you want?
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Check yourself: Efficacy in context
Before adopting the new reading program district-wide, the school board asked for evidence of its ______: did students who used it actually read better?
Answer: efficacy. The question "did students actually read better?" asks whether the program produces the intended result, which is its efficacy. Evidence of a guess, a support or an eclipse makes no sense here.
Farmers doubted the ______ of the cheaper pesticide until a two-year field trial showed it controlled beetles as well as the standard product.
Answer: efficacy. The trial tested whether the pesticide worked as intended, so the farmers doubted its effectiveness. The other nouns don't describe how well a product works.