The word “cardinal” has several related meanings, but they all lean toward the idea of something central, primary, or important.

Main meanings of “cardinal”

  • A senior official in the Roman Catholic Church, ranking just below the pope and belonging to the College of Cardinals.
  • A bright red North American songbird, especially the male, known simply as “a cardinal.”
  • A basic or most important principle or rule, as in “cardinal rule” or “cardinal principle,” meaning something fundamental that should not be broken.
  • A cardinal number in mathematics, like 1, 2, 3, used to show quantity rather than order (as opposed to ordinal numbers like first, second, third).

Underlying idea

Across these uses, “cardinal” often carries the sense of “central” or “essential”:

  • Cardinals in the Church form a central governing body.
  • Cardinal rules or sins are the most important ones.
  • Cardinal numbers are the basic counting numbers learned first in math.

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