cardinal

Crested thick-billed North American finch having bright red plumage in the male.

The number of elements in a mathematical set; denotes a quantity but not the order.

A variable color averaging a vivid red.

(Roman Catholic Church) one of a group of more than 100 prominent bishops in the Sacred College who advise the Pope and elect new Popes.

Serving as an essential component.

“a cardinal rule”

Being or denoting a numerical quantity but not order.

“cardinal numbers”