efficacious

Adjective (2)

1. 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”
2. 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 — LewisMumford”“effective teaching methods”“effective steps toward peace”“made an effective entrance”“his complaint proved to be effectual in bringing action”“an efficacious law”Synonyms: effectiveeffectual