early 12c., "one of the ecclesiastical princes who constitute the sacred college," from L. cardinalis "principal, chief, essential," from cardo (gen. cardinis) "that on which something turns or depends," originally "door hinge." Ecclesiastical use began for the presbyters of the chief (cardinal) churches of Rome. The adj. sense of "chief, principal" in English is attested from mid-15c. Cardinal points (1540s) are "north, south, east, west." The cardinal virtues (c.1300) were divided into natural (justice prudence, temperance, fortitude) and theological (faith, hope, charity). The N.Amer. songbird (Cardinalis virginianus) is attested from 1670s, so named for its resemblance to the red robes of the cardinals.