Why are cardinals called cardinals?

Cardinals (not the ornithological kind) are much in the news these days. But why are they called cardinals?

The Latin word for "hinge" was  cardo, with its accusative case being cardinem. From this derived an adjective describing hinge-related things, cardinālis. The fixed hinge around which things turn is of necessity, very important -- that's why we use the phrase "to hinge upon something" -- so cardinālis took on the meaning "fundamental, principal, of chief importance".  

Some of the things the Romans described as "cardinal" were the winds from the four compass points and cardinal numbers.

But very early on in church history, particularly important priests in the hierararchy were also described with the adjective "cardinal", which subsequently became a noun.

The Catholic Church also used the adjective "cardinal" to designate the most important virtues (in scholastic philosophy, justice, prudence, temperance, and fortitude,considered  the four chief ‘natural’ virtues as distinguished from the ‘theological’ virtues of faith, hope, and charity).

To balance the virtues there are of course the seven deadly sins, and these came to be known as cardinal sins. Entertainingly, the chief Catholic archbishop in the Philippines a while ago had the infelicitous name Cardinal Sin.

Why do cardinals wear red? In the 13th century Pope Innocent IV granted them the privilege of wearing a red hat. Subsequently, no doubt, they wanted a matching ensemble. Scarlet is the traditional colour for church vestments worn on martyrs' feast days, to commemorate the shedding of their blood for the church, and has the same symbolic meaning in the attire of cardinals, who are meant to be willing to give of themselves for the Church, even to the point of martyrdom.
  
When the English started settling in the Carolinas in the 1700s and saw the brilliant scarlet plumage of the native bird, they instantly saw a resemblance to a cardinal's clothing and named the bird accordingly. 
 

And speaking of feathered things, there is apparently a French proverb, particularly apposite at the moment, which translates as "He who enters the conclave as Pope leaves it as a cardinal", in other words, the guy who seems to be the frontrunner in the election turns out to be a loser, or, by extension, don't count your chickens -- or your cardinals -- till they're hatched.

To find out why the adjective is "papal" though the noun is "pope", click here.

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