cardinal

Etymology

From Middle French cardinal, from Latin cardinālis (“pertaining to a hinge, hence applied to that on which something turns or depends, important, principal, chief”), from cardō (“hinge”) + -ālis, adjectival suffix.

adj

1. Of fundamental importance; crucial, pivotal.
   a cardinal rule
   Impudence is now a cardinal virtue. a. 1631, Michael Drayton, To my noble friend Mr. William Brown, of the evil time
2. (nautical) Of or relating to the cardinal directions (north, south, east and west).
   a cardinal mark
3. Describing a "natural" number used to indicate quantity (e.g., zero, one, two, three), as opposed to an ordinal number indicating relative position.
4. Having a bright red color (from the color of a Catholic cardinal's cassock).

noun

1. (Roman Catholicism) One of the officials appointed by the pope in the Roman Catholic Church, ranking only below the pope and the patriarchs, constituting the special college which elects the pope. (See Wikipedia article on Catholic cardinals.)
   His uncle, a Cardinal, engages a Spanish youth of Moorish descent called Diego, an expert singer and player on the virginal, to unlock the secrets of the heart,[…]and cure him by the spell of his music. 1932, Maurice Baring, chapter 16, in Friday's Business
2. Any of a genus of songbirds of the finch family, Cardinalis.
3. Any of various related passerine birds of the family Cardinalidae (See Wikipedia article on cardinals) and other similar birds that were once considered to be related.
4. (color) A deep red color, somewhat less vivid than scarlet, the traditional colour of a Catholic cardinal's cassock. (same as cardinal red)
   cardinal:
   The cardinal red and silver grey colors were worn with great enthusiasm. In the spring-time, when the entire student body bought their new straw hats, the bands were of cardinal and grey ribbon. 1914, ἄν ἀνἁβιλε, “Under the Cardinal Red and Silver Grey”, in Corks and Curls, volume 27, University of Virginia, page 28
5. (mathematics) Short for cardinal number, a number indicating quantity, or the size of a set (e.g., 0, 1, 2, 3). (See Cardinal_number.)
   This cardinal number is the smallest of the infinite cardinal numbers; it is the one to which Cantor has appropriated the Hebrew aleph with the suffix 0, to distinguish it from larger infinite cardinals. Thus the name of the smallest of infinite cardinals is ₀א. 1920, Bertrand Russell, Introduction to Mathematical Philosophy, page 83
6. (grammar) Short for cardinal numeral, a word used to represent a cardinal number.
   The commonest numerals in Latin, as in English, are the "cardinals" […] and the "ordinals" […]. 2005, Frederic M. Wheelock, Wheelock's Latin, 6th ed. revised, p.97
7. Short for cardinal flower (Lobelia cardinalis), a flowering plant.
   The sweet-briar rose with perfume good, / And the violet grows in the Milton wood, / The cardinal red—a queen is she, / But the sweetest flower is Mary Lee. 1844–1857, Marion D. Sullivan (lyrics and music), “Mary Lee: A Romance of the Milton Wood” (sheet music), Boston: Oliver Ditson, page 2, verse 3
8. Short for cardinal tetra (Paracheirodon axelrodi), a freshwater fish.
9. (now historical) A woman's short cloak with a hood, originally made of scarlet cloth.
   […]; and whilst she was looking over several pieces of each, she took an opportunity of concealing under her cardinal a piece of cotton, and several handkerchiefs, with which she went off undiscovered;[…]. 1763-08-09, The London Chronicle For the Year 1763, volume 14, page 130, column 2
   She has valuables of mine; besides, my cardinal and veil are in her room. 1775, Richard Brinsley Sheridan, The Duenna, I.3
   Where's your cardinal! Make haste. c. 1760, Robert Lloyd, Chit-Chat, an imitation of Theocritus
   I have made no objection to their wearing the cardinal, though it be a habit of popish etymology, and was, I am afraid, first invented to hide the sluttishness of French dishabille. 1823, Lionel Thomas Berguer, World, page 115
10. (obsolete) Mulled red wine.
    He goes up, and finds the remains of the supper, Tankards full of egg-flip and cardinal, and a party playing at vingt-un. 1861, Thomas Hughes, Tom Brown at Oxford
    A Recipe to make Cardinal, which I attribute to the German governess, raises a problem. 1951, Herbert Warner Allen, A Contemplation of Wine, page 116
    It was de Rosenberg's practice to separate young bloods from their inheritance, and to facilitate this he served them a vicious drink called 'cardinal', a mulled wine of which the ascertainable ingredients were a pineapple and several mixed vintages. 1974, Dennis Walton Dodds, Napoleon's Love Child: A Biography of Count Leon, page 59