Cardinal

a. [Fr. cardinal, Lat. cardinalis, from cardo, the hinge of a door, that about which a thing revolves, on which it depends, the chief point or circumstance.] Of fundamental importance; pre-eminent; superior; chief; principal.

Impudence is now a cardinal virtue. Drayton.

Cardinal numbers, the numbers one, two, three, &c., in distinction from first, second, third, &c., which are called ordinal numbers.—Cardinal points. (a.) (Geog.) The four intersections of the horizon with the meridian, and the prime vertical circle, or north and south, east and west. (b.) (Astrol.) The rising and setting of the sun, the zenith and nadir.—Cardinal signs (Astron.), Aries, Libra, Cancer, and Capricorn.—Cardinal virtues (Antiq.), prudence, justice, temperance, and fortitude.—Cardinal winds, those which blow from the cardinal points.