V2 Vocabulary Building Dictionary



Definition: effectiveness and ability to yield a planned and desired result

Synonyms: effectiveness, efficiency, efficaciousness

Antonyms: inefficacy, ineffectiveness

Tips: Efficacy is sometimes alternated with efficaciousness. Efficacy is often used when referring to a drug or treatment's medical effectiveness. If something is described as efficacious, it works. Efficacy is often just a simpler, more sophisticated way of saying effectiveness. The related adjective efficacious means "effective."

Usage Examples:

The FDA is concerned with both safety and efficacy when it comes to approving new pharmaceuticals. (effectiveness)

The new drug is considered both safe and efficacious by the FDA. (effective) adjective

The efficacy of your innovative learning system is clear from the test results. (effectiveness)

The efficacy of the new cancer treatment has not been proven. (effectiveness)

Want to Learn More Words Like efficacy?
Discover How You Can Improve Your
Vocabulary 10 to 100 Times Faster with
the Power Vocabulary Builder

Dear Friend,

The definition and lessons for the word efficacy were made available by the Power Vocabulary Builder.

The Power Vocabulary Builder will help you develop a fuller, richer vocabulary 10 to 100 times faster than any other program available.

Visit the the Power Vocabulary Builder site right now to discover how you can get full access to this breakthrough program today!

What's your vocabulary level?
Power Vocabulary Builder
FREE E-mail Course!

Drop your details in the boxes below to receive a FREE vocabulary course: