I.efficacious, effectual, powerful, efficient (mostly postAug.; not in Cic. and Caes; but cf. efficacitas): nosti Marcellum, quam tardus et parum efficax sit, Cael. ap. Cic. Fam. 8, 10, 3; cf.: “ultor contemptae religionis,” Val. Max. 1, 1, 19: “Hercules,” Hor. Epod. 3, 17: “scientia (magica),” id. ib. 17, 1: “preces,” Liv. 9, 20: “studium promerendi amoris,” Suet. Calig. 3 init.: “breve et efficax iter est per exempla,” Sen. Ep. 6, 5: “admonitiones,” id. ib. 8, 2 al.: “herba in dolore stomachi,” Plin. 27, 13, 109, § 136: “preces ad muliebre ingenium,” Liv. 1, 9 fin.; so with ad, Sen. Ben. 2, 7 fin.; cf. in the comp., Quint. 6, 1, 41; Plin. Pan. 84: “elatine oculorum fluxionibus efficax,” Plin. 27, 9, 50, § 74; so with dat., id. 28, 14, 58, § 204; in the sup.: “continuatio in peragendis rebus,” Liv. 41, 15: “frutex efficacissimus contra sagittarum ictus,” Plin. 13, 21, 36, § 115; cf.: herba adversus serpentium venena, id. 24, 15, 80, § 130: “ad excitandam virtutem, etc.,” Vell. 1, 8, 1. —Poet., with inf.: “(cadus) amara Curarum eluere efficax,” Hor. C. 4, 12, 20; Val. Max. 2, 7, 10: “cum sit efficacissimum de integro locum exarare,” Col. 2, 17, 3: “efficacissimum est hic quoque salem superponere,” Cels. 4, 4, 16; 4, 22, 11.—Hence, adv.: effĭcācĭter , effectually, powerfully, Quint. 5, 13, 25; Sen. Brev. Vit. 6 et saep.—Comp., Quint. 8, 4, 8; Tac. G. 8; Plin. Ep. 6, 6, 8; Plin. 24, 6, 14, § 23.— Sup., Plin. 26, 12, 79, § 128; 24, 6, 14, § 23; id. Ep. 2, 13 fin.
effĭcax , ācis, adj. efficio,