cardinal

Cardinal is a term used in multiple, largely related senses. It derives from the Latin cardinalis meaning principal or hinge, and from cardo “hinge,” reflecting the idea of something central or fundamental. The word appears in mathematics, religion, philosophy, and everyday language to denote importance or principal status.

In geography and navigation, cardinal directions are the four main points that define orientation: north, east, south, and west. They serve as reference points for maps, compasses, and navigation, and can be extended with intercardinal directions (northeast, etc.) to describe intermediate bearings.

In mathematics, cardinal numbers express quantity, such as one, two, and three. They contrast with ordinal numbers, which express order (first, second). The concept of cardinality measures the size of a set; finite sets have a finite cardinality, while infinite sets have larger and more complex cardinalities, often described using symbols like aleph null.

In the Roman Catholic Church, a cardinal is a senior official who typically is a bishop or archbishop and is appointed by the pope. Cardinall is a member of the College of Cardinals and participates in papal conclaves to elect a pope, among other duties.

Cardinal virtues are a traditional grouping of four core moral qualities: prudence, justice, temperance, and fortitude. The term cardinal is sometimes used in reference to the seven cardinal sins, more commonly known as the seven deadly sins, which have historically been described as fundamental moral failings.

The word also appears in color and wildlife: the cardinal is a bright red color named after the robes worn by cardinals, and the northern cardinal is a conspicuous red bird common in North America, recognizable by the male’s vivid plumage.