1. Power or capacity to produce effects; power to effect the object intended. (Not used as an attribute of personal agents: cf. EFFICACIOUS.)
1527. Andrew, Brunswyke’s Distyll. Waters, Prol. Charmes of eficacye unnaturall by the devyll envented.
1532. More, Confut. Barnes, VIII. Wks. (1557), 740/2. Theffect and effecacy of al these thynges, commeth of God.
1563. T. Hyll, Arte Garden. (1593), 157. And the seedes may well be kept for three yeares in good efficacie.
1646. Sir T. Browne, Pseud. Ep., I. x. 40. An act [not] … beyond the efficacy of the Sun.
1744. Berkeley, Siris, § 4. 5. A medicine of such efficacy in a distemper attended with so many purulent ulcers.
1750. Johnson, Rambl., No. 47, ¶ 11. The efficacy of mirth it is not always easy to try.
1792. in Chipman, Amer. Law Rep. (1871), 55. The division was not taken to have any legal efficacy.
1844. H. H. Wilson, Brit. India, II. 553. To maintain the village institutions of the country in entireness and efficacy.
1856. Froude, Hist. Eng. (1858), I. ii. 103. No measures would be of efficacy which spared the religious houses.
† 2. A process or mode of effecting a result. Obs.
1690. Locke, Hum. Und., II. xxii. § 11 (1695), 156. The Efficacy whereby the new Substance or Idea is produced, is called, in the subject exerting that Power, Action; but in the subject, wherein any simple Idea is changed or produced, it is called Passion. Ibid., IV. iii. § 24. 277. We are ignorant of the several Powers, Efficacies, and Ways of Operation, whereby the Effects we daily see, are produced.
† 3. a. Effect. b. ? Actual event. Obs.
1549. Latimer, Serm. bef. Edw. VI., v. O iiij. You by youre prayer can worcke greate efficacye.
a. 1613. Overbury, Characters (1638), A Puritane, His arguing is but the efficacy of his eating.
1633. Bp. Hall, Hard Texts, 350. In the efficacy of his appearance, he shall be so glorious.
