"Efficacy" is a word in ENGLISH

Having sufficient power, force, or efficacy, for the object; effectual; valid; as, an available plea.

Competent power; validity; efficacy; as, the availableness of a title.

Acting rapidly and violently; efficacious; powerful; -- opposed to bland; as, drastic purgatives.

Possessing the quality of being effective; productive of, or powerful to produce, the effect intended; as, an efficacious law.

Exhibiting energy; operating with force, vigor, and effect; forcible; powerful; efficacious; as, energetic measures; energetic laws.

Possessing force; characterized by force, efficiency, or energy; powerful; efficacious; impressive; influential.

Not efficacious; not having power to produce the effect desired; inadequate; incompetent; inefficient; impotent.

Exerting or possessing influence or power; potent; efficacious; effective; strong; having authority or ascendency; as, an influential man, station, argument, …

To hinder; to destroy; as, to infringe efficacy; to infringe delight or power.

Mastery; powerful medical influence; renowned efficacy; a sovereign remedy.

The quality or state of being potent; physical or moral power; inherent strength; energy; ability to effect a purpose; capability; …

Producing great physical effects; forcible; powerful' efficacious; as, a potent medicine.

With great force or energy; powerfully; efficaciously.

The quality or state of being potent; powerfulness; potency; efficacy.

Full of power; capable of producing great effects of any kind; potent; mighty; efficacious; intense; as, a powerful man or …

Having the power of acting or of invisible efficacy without the agency of the material or sensible part; potential; energizing.

Active quality or power; capacity or power adequate to the production of a given effect; energy; strength; potency; efficacy; as, …

Having power or efficacy; powerfully operative; efficacious; potent.

Importance; power; influence; efficacy; consequence; moment; impressiveness; as, a consideration of vast weight.