1. A line segment that joins the center of a circle with any point on its circumference. 2. A line segment that joins the center of a sphere with any point on its surface. 3. A line segment that joins the center of a regular polygon with any of its vertices. 4. The length of any such line segment. 5. every family within a radius of 25 miles of the city center. 6. the operating radius of a helicopter. 7. A radial part or structure, such as a mechanically pivoted arm or the spoke of a wheel. 8. A long, prismatic, slightly curved bone, the shorter and thicker of the two forearm bones, located on the lateral side of the ulna. 9. A similar bone in many vertebrates.
