marked by qualities giving the power to produce an intended effect; written propaganda is less efficacious than the habits and prejudices...of the readers-Aldous Huxley; the medicine is efficacious in stopping a cough'

producing or capable of producing an intended result or having a striking effect; an air-cooled motor was more effective than a witchs broomstick for rapid long-distance transportation-LewisMumford; effective teaching methods; effective steps toward peace; made an effective entrance; his complaint proved to be effectual in bringing action; an efficacious law

[ Syn: effective , effectual ]