Efficacy
ˈɛfɪkəsi
Definitions
The power or capacity to produce a desired effect; the degree to which something works.
ˈɛfɪkəsi
The ability to produce a desired or intended result; effectiveness.
The efficacy of the new vaccine was confirmed in numerous studies.
💡 Simply: Imagine you're trying a new recipe. If it turns out exactly as you hoped, with everyone loving it, then the recipe had *efficacy*! It did what it was supposed to do.
👶 For kids: When something is working really well and doing what it's supposed to, like when your medicine helps you feel better, that medicine has efficacy!
More Examples
Researchers are investigating the efficacy of alternative therapies.
The company is constantly trying to improve the efficacy of its products.
How It's Used
"The clinical trials demonstrated the efficacy of the new drug in treating the disease."
"The marketing team evaluated the efficacy of different advertising campaigns."
"The efficacy of the new teaching methods was immediately apparent in the students' test scores."
Idioms & expressions
in the efficacy of
Believing in the effectiveness of something.
"She put all her efforts in the efficacy of the new approach."
demonstrate efficacy
To prove or show how well something works
"The clinical trials were designed to demonstrate the efficacy of the new treatment."
From Latin *efficacia*, meaning 'effectiveness' or 'power to produce an effect,' derived from *efficax* 'effective,' from *ex-* 'out' + *facere* 'to do, make.'
Efficacy has been used since the 16th century, primarily in scientific and philosophical contexts.
Memory tip
Think of 'effect' – efficacy is about how well something actually *works* and produces the intended effect.
Practice
Word Origin
Root: efficax