- an air-cooled motor was more effective than a witch's broomstick for rapid long-distance transportation.
- an efficacious law.
- effective steps toward peace.
- effective teaching methods.
- his complaint proved to be effectual in bringing action.
- made an effective entrance.
- the medicine is efficacious in stopping a cough.
- written propaganda is less efficacious than the habits and prejudices...of the readers.