Why do they call north, south, west, east cardinal directions?

North, South, East, and West are called the "Cardinal Direction" because they are not only the main directions, but other directions like North-East, South-East, etc are based off of them.

It's very similar to the "Cardinal Colors" (aka: Primary Colors) in art. Those are Red, Yellow, and Blue, but every other color is based off of those 3.

I hope this helps!