Why are the points of a compass called "cardinal" directions?

Answer 1

North, South, East and West are called the "cardinal" points of the compass, because they are the main or principle ones on which the rest are based.

"cardinal" comes from Late Latin "cardinalis" meaning "principal, pivotal"

http://www.thefreedictionary.com/cardinal

Answer 2

The word 'cardinal' means denoting that on which a thing hinges or depends. Fundamental.
amongst other things. The word originates from the Latin 'cardinalis' meaning a hinge, also cardo and cardinis.
Thus the 'Cardinal Points' are those on which the remaining points of the compass depend. There are 32 points of the compass all of which depend on the four main ones, North, East, South and west and every direction is a combination of these. For example those between North and West would be, in order.
North
North by West
North by North West
North West by North
North West
North West by West
West by North West
West by North

This principle continues around the compass until all 32 points are listed.
West

Answer 3

In St.Louis, all directions lead to the Cardinals
or is it that all roads lead to Rome-the home of the [College of ] Cardinals???

Or that it is derived from the Latin for chief, important

Answer 4

I tried to get them to call them Blue Jay directions, but I was overruled.