Why radius is called radius?

Answer 1

Radius The word radius was a Latin word for the spoke of a wheel. The similarity of radius to the Indo-European root werad from which we get radical and rhizome and the image of the roots of a plant spreading out in all directions like the spokes of a wheel seem too much to resist. Whatever its origin, the word radius was shortened to produce ray, and is also the source of the word radio, named because the electromagnetic rays radiate out in every direction.