radius

(noun) the length of a line segment between the center and circumference of a circle or sphere. Synonyms: r.

(noun) a straight line from the center to the perimeter of a circle (or from the center to the surface of a sphere).

(noun) a circular region whose area is indicated by the length of its radius. Examples: "They located it within a radius of 2 miles."

(noun) the outer and slightly shorter of the two bones of the human forearm.

(noun) support consisting of a radial member of a wheel joining the hub to the rim. Synonyms: spoke, wheel spoke.