The word cardinal comes from the Latin cardo for "hinge" and usually refers to things of fundamental importance, as in cardinal rule or cardinal sins.

• In mathematics, cardinal is short for cardinal number.

• In Catholicism, a cardinal is a prince of the Church; cardinals are appointed by the Pope and collectively elect the next Pope if they are under the age of eighty at the time of the election. See Cardinal (Catholicism).

• Cardinal (color) is a bright red color like the color of the robe of a cardinal.

• In ornithology, a cardinal is a songbird of the family Cardinalidae or more often the genus Cardinalis, in North America especially the Northern Cardinal, C. cardinalis. Males of this species are cardinal red, hence the name.

• In sports, the Cardinals are:
  • A baseball team in St. Louis, Missouri (see St. Louis Cardinals).
  • An American football team in Arizona (see Arizona Cardinals).
  • The mascot for the Kentucky based University of Louisville intercollegiate sports teams.
  • The mascot for the South Carolina based Landrum High School intercollegiate sports teams.
  • Furthermore, the Cardinal (singular, referring to the color) is the mascot for teams from Stanford University, California .

• Cardinal is a Swiss beer brand.

• Douglas J Cardinal is a renowned Canadian architect.

• The Cardinal was a named passenger train operated by the Chicago & Eastern Illinois railroad between Chicago and St. Louis, MO.

There are places that have the name Cardinal in North America

• Cardinal, Ontario
• Cardinal , a settlement in Mathews County, Virginia