Meaning: capacity or power to produce a desired effect; "concern about the safety and efficacy of the vaccine"
It might allege a necessity of doing this in order to give efficacy to the national revenues.
The peace of society and the stability of government depend absolutely on the efficacy of the precautions adopted on this head.
The poor woman evidently believed in its efficacy; her only feeling was indignation that her cat had been chosen out from all others for a sacrifice.
Pliny has expressed belief in the efficacy of the fasting spittle for curing disease, and referred to the custom of spitting to avert witchcraft. In England, Scotland, and Ireland spitting customs are not yet obsolete.
Things which are produced by external causes, whether they consist of many parts or few, owe whatsoever perfection or reality they possess solely to the efficacy of their external cause; and therefore their existence arises solely from the perfection of their external cause, not from their own.
In order to prove the efficacy of this apparatus, and inspire the firemen with confidence in its protection, he showed them that a finger first enveloped in asbestos, and then in a double case of wire-gauze, might be held a long time in the flame of a spirit-lamp or candle before the heat became inconvenient.
They hold that to act with efficacy upon the press it would be necessary to find a tribunal, not only devoted to the existing order of things, but capable of surmounting the influence of public opinion; a tribunal which should conduct its proceedings without publicity, which should pronounce its decrees without assigning its motives, and punish the intentions even more than the language of an author.