Definitions of cardinal:

  • noun:   crested thick-billed North American finch having bright red plumage in the male
  • noun:   a variable color averaging a vivid red
  • noun:   (Roman Catholic Church) one of a group of more than 100 prominent bishops in the Sacred College who advise the Pope and elect new Popes
  • noun:   the number of elements in a mathematical set; denotes a quantity but not the order
  • adjective:   serving as an essential component
    Example: "A cardinal rule"
  • adjective:   being or denoting a numerical quantity but not order
    Example: "Cardinal numbers"
  • name:  A surname (rare: 1 in 100000 families; popularity rank in the U.S.: #7622)