Cardinal is a term with several principal senses in religion, nature, colour, mathematics and general language. The word traces to Latin cardinalis, "principal" or "of hinging importance," reflecting its use for things regarded as chief, foundational, or distinguishing in a system.
Religious office
In the Roman Catholic Church a cardinal is a senior cleric appointed by the pope to serve as a principal advisor and to form the College of Cardinals. The college has roles in governance of the Church and in electing a new pope in a conclave. Cardinals are commonly associated with red vestments and a red hat, a colour long linked with their office; the red is traditionally said to symbolise readiness to defend the faith. Within the college there are historical distinctions of rank and title used for ceremonial and administrative purposes.
Birds (family Cardinalidae)
The name also identifies a group of seed-eating passerine birds in the family Cardinalidae. The best-known species to many is the Northern cardinal, a familiar backyard bird in eastern and central North America noted for the male's vivid red plumage and crest and for the female's more subdued tones. Members of the family include cardinals, grosbeaks and some buntings; they are valued by birdwatchers for conspicuous colours, clear songs and often bold behaviour at feeders. Many species occupy woodland edges, scrub and gardens and feed on seeds, fruits and insects.
Colour and symbolism
As a colour name, cardinal denotes a deep vivid red associated with the traditional robes of Catholic cardinals. The hue is used in academic dress, national and regional flags, corporate and sports branding. Because of its association with high rank and visibility, "cardinal" is often used metaphorically to mean chief or fundamental, as in a "cardinal rule" or "cardinal principle."
Mathematics and other senses
In mathematics a cardinal number indicates the size or cardinality of a set, expressing how many elements it contains. Set theory distinguishes finite and infinite cardinalities and uses specific notation and concepts to compare sizes of infinite sets. The contrast between cardinal and ordinal numbers—counting size versus position—reflects two different ways to describe sets.
Other uses and examples
- Cardinal virtues: a classical grouping of primary moral virtues.
- Cardinal points: the main directions on a compass (north, south, east, west).
- Sports and culture: "Cardinals" is a common team name drawing on the colour or symbolism (for example in professional baseball and football), and some institutions use "Cardinal" to refer to a shade in their identity.
Because the term links to the idea of centrality and prominence, it appears widely across languages and domains to mark what is viewed as essential or leading in a given context.