cardinal

noun

• 1a leading dignitary of the Roman Catholic Church. Cardinals are nominated by the Pope, and form the Sacred College which elects succeeding popes (now invariably from among their own number): his appointment as cardinal [as title]:the Cardinal Archbishop of Westminster
• (also cardinal red) [mass noun] a deep scarlet colour like that of a cardinal’s cassock.

• 2a New World songbird of the bunting family, having a stout bill and typically a conspicuous crest. The male is partly or mostly red in colour.

  • Family Emberizidae, subfamily Cardinalinae (the cardinal grosbeak subfamily): four genera and several species

adjective

• of the greatest importance; fundamental:two cardinal points must be borne in mind