efficace
Efficace is an adjective used in Italian and French to describe something that produces the intended result or has a strong effect. In Italian it commonly describes actions, methods, medicines, policies, and performances: un metodo efficace, un farmaco efficace. In French the same sense applies: une mesure efficace, un traitement efficace. In both languages, the term emphasizes effectiveness rather than speed, though in practice it can imply practical success in real-world use. The word forms differ by language: Italian uses efficace in the singular for both genders and efficaci in the plural; French uses efficace in the singular for both genders and efficaces in the plural.
Etymology traces efficace to Latin efficax, from efficere, meaning “to accomplish, to bring about.” The Latin
Usage notes and nuance: in medicine and science, the related noun forms efficiency or efficacy convey the