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 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).
- In ornithology, a cardinal is the songbird Cardinalis cardinalis. They are red, similar to the dress of cardinals in the catholic church, hence the name. Cardinals belong to the finch family.
- Cardinal is a bright red color like the color of the robe of a cardinal.
Cardinal is a Swiss beer brand.