marked by qualities giving the power to produce an intended effect
Written propaganda is less efficacious than the habits and prejudices...of the readers. The medicine is efficacious in stopping a cough.
source: WordNet 3.0
producing or capable of producing an intended result or having a striking effect
An air-cooled motor was more effective than a witch's broomstick for rapid long-distance transportation. Effective teaching methods. Effective steps toward peace. Made an effective entrance. His complaint proved to be effectual in bringing action. An efficacious law.
source: WordNet 3.0
Possessing the quality of being effective; productive of, or powerful to produce, the effect intended; as, an efficacious law.
