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1. Of foremost importance; paramount: a cardinal rule; cardinal sins.
2. Dark to deep or vivid red.
1. Abbr. Card. Roman Catholic Church A high church official, ranking just below the pope, who has been appointed by a pope to membership in the College of Cardinals.
2. A dark to deep or vivid red.
3. A North American bird (Cardinalis cardinalis) having a crested head, a short thick bill, and bright red plumage in the male.
4. A short hooded cloak, originally of scarlet cloth, worn by women in the 1700s.
5. A cardinal number.
[Middle English, from Late Latin cardinālis, principal, pivotal, from Latin, serving as a hinge, from cardō, cardin-, hinge.]