cardo, ĭnis, m. [cf. κράδη, a swing; κραδαίνω, to swing, wave; Sanscr. kurd, a spring, a leap; old Germ. hrad, lively, and Germ. reit in bereit, ready] (f., Gracch. ap. Prisc. p. 683 P.; Graius ap. Non. p. 202, 20; cf. infra in Vitr.),
I the pivot and socket , upon which a door was made to swing at the lintel and the threshold , the hinge of a door or gate , Enn. Trag. 119 Vahl.: paene ecfregisti foribus cardines, Plaut. Am. 4, 2, 6; id. As. 2, 3, 8: postis a cardine vellit Aeratos, Verg. A. 2, 480: cardo stridebat, id. ib. 1, 449; cf. id. Cir. 222: num muttit cardo? Plaut. Curc. 1, 1, 94: immoti, Plin. 16, 43, 84, § 230: singuli, id. 36, 15, 24, § 117: facili patuerunt cardine valvae, Juv. 4, 63: versato cardine Thisbe Egreditur, opening the door , Ov. M. 4, 93; cf. Verg. A. 3, 448: nec strepitum verso Saturnia cardine fecit, Ov. M. 14, 782 al.—
B Meton.
1 Cardines, in mechanics, beams that were fitted together; and specifically, cardo masculus, a tenon , Vitr. 9, 6, and cardo femina, a socket , a mortise , id. 9, 6: cardo securiclatus, axeshaped tenon , a dovetail , id. 10, 15, 3.— Hence,
b In garlands, the place where the two ends meet , Plin. 21, 4, 10, § 18.—
2 In astron., the point about which something turns , a pole. So of the North pole : caeli, Varr. R. R. 1, 2, 4: mundi, Plin. 4, 12, 26, § 89; cf.: extremusque adeo duplici de cardine vertex Dicitur esse polus, Cic. poët. N. D. 2, 41, 105; Ov. P. 2, 10, 45; Stat. Th. 1, 349: cardo glacialis ursae, Sen. Herc. Fur. 1139: Arctoae cardo portae, Stat. Th. 7, 35; hence anal. to this, with the agrimensores, the line limiting the field , drawn through from north to south , Plin. 18, 33, 76, § 326; 17, 22, 35, § 169; cf. Fest. s. v. decimanus, p. 71 Müll., and accordingly the mountain Taurus is called cardo, i. e. line or limit , Liv. 37, 54, 23; cf. id. 40, 18, 8; 41, 1, 3.—Of the four cardinal points of the world , Quint. 12, 10, 67; so, Hesperius Eous, Luc. 5, 71; Stat. Th. 1, 157: occiduus, Luc. 4, 672: medius, id. 4, 673.— Of the earth as the centre of the universe , acc. to the belief of the ancients, Plin. 2, 64, 64, § 160; 2, 9, 6, § 44.—Of the intersection of inclined surfaces : reperiuntur (aquae) ... quodam convexitatis cardine aut montium radicibus, Plin. 31, 3, 26, § 43.—Of the summer solstice : anni, Plin. 18, 28, 68, § 264; and so of the epochs of the different seasons : temporum, id. 18, 25, 58, § 218; 18, 25, 59, § 220.—Hence, of the time of life : extremus, old age , Luc. 7, 381.—
II Trop., that on which every thing else turns or depends , the chief point or circumstance (so not before the Aug. per.): haud tanto cessabit cardine rerum, at such a turn of affairs , so great a crisis , in so critical a moment , decisive , Verg. A. 1, 672 (hoc est in articulo, Serv.; cf. Isid. Orig. 15, 7, 6; Gr. ἀκμ): fatorum in cardine summo, Stat. Th. 10, 853: litium. Quint. 12, 8, 2: causae, id. 5, 12, 3: satellitem in quo totius dominationis summa quasi quodam cardine continetur, Val. Max. 3, 3, ext. 5: unum eligamus in quo est summum ac principale, in quo totius sapientiae cardo versatur, Lact. 3, 7, 6.