Why do they call them cardinal directions?

"Cardinal" in this sense means "primary" or "of most importance". They are the cardinal directions because they lay out the basic grid, and all other directions are given relative to them. This is the sense of the word that also yields "cardinal number", i.e. 0, 1, 2.... read more

The word cardinal is derived from the Latin name "cardo", which identified, in Roman cities, the street traced from north to south and passing through the center of the city. read more

"Cardinal" comes from the early 14th century and was derived from the Latin cardinalis ("principal, chief, essential"). read more