what does roduis mean
raâ¢diâ¢us. 1. a straight line extending from the center of a circle or sphere to the circumference or surface: The radius of a circle is half the diameter. 2. the length of such a line. 3. any radial or radiating part.. A line segment that joins the center of a circle or sphere with any point on the circumference of the circle or the surface of the sphere. It is half the length of the diameter. 2.