Wikipedia: Cardinal

1. In mathematics, cardinal is short for cardinal number.
2. In Catholicism, a cardinal is a prince of the Church; cardinals are appointed by the Pope and get to vote for the next Pope if they are under the age of eighty at the time of the election.
3. In biology, a cardinal is the songbird Cardinalis cardinalis. They are red, similar to the dress of cardinals in the catholic church, hence the name.
4. In sports, the Cardinals are a baseball team in St. Louis (see Saint Louis Cardinals), an American football team in Arizona (see Arizona Cardinals), and a college team from Stanford, California.