Radial things stick out from a center point or have to do with the radius of a circle. On a map, you can see that a traffic circle or roundabout consists of radial streets extending out from the center.
A radius is a line from the center of a circle to its edge, or circumference. The adjective radial describes anything that acts as a radius or resembles one — often something radial is literally a line sticking straight out from a center point. Radial tires are designed so that each individual rubber cord making up the tire's surface lies in a radial direction from the middle of the tire. In Latin, radius means "shaft" or "spoke of a wheel."