The history of the word cardinal in English is rather interesting. It comes from the Latin cardinalis, meaning “chief, principal.” But it first came over to English not as an adjective with that meaning, but as the noun–as in, the order in the Church. Since the 12th century, we’ve had the word cardinal as an “ecclesiastical prince who constitutes the sacred college.”
So when did the adjective join the fun? Not until the 14th century! I find it rather interesting that though taken from the Latin adjective, we didn’t adopt that adjective form for two hundred years. Because it means “principal, pivotal, something on which things hinge,” it has occasionally been applied to literal hinges. But what know it more for is its uses in things like cardinal numbers (whole numbers, the ones on which others rely) like one, two, three, twenty, etc (1590s); the cardinal points or directions–north, south, east, west (1540s); and cardinal sins (1600s). Did you know there are also cardinal virtues? They date from the 1300s and include justice, prudence, temperance, and fortitude, and then adding in faith, hope, and charity.
The bird we’ve called the cardinal is so named because its bright red feathers are reminiscent of the bright red robes of the cardinals in the Church.