efficacious

Adjective

• 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
    

• 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
    

Related words

• Synonyms: 
  effective , effectual
• Antonyms: 
  ineffective , uneffective , ineffectual , inefficacious