Effect and Efficacy

Effect noun - A condition or occurrence traceable to a cause.

Efficacy is a synonym for effect in impact topic. In some cases you can use "Efficacy" instead a noun "Effect", when it comes to topics like thing, affect, effectiveness.

Nearby Words: effective, effectual, effected, effectively, effecting

Efficacy noun - The power to produce a desired result.

Effect is a synonym for efficacy in thing topic. You can use "Effect" instead a noun "Efficacy", if it concerns topics such as affect, effectiveness, efficiency.

Nearby Words: efficient, efficiency, efficacious, efficaciously, efficaciousness