1. A straight line from the centre to the perimeter of a circle (or from the centre to the surface of a sphere)
   "The radius of the circle was 5 centimetres"
    
2. The length of a line segment between the centre and circumference of a circle or sphere
   "The radius of the circle was half the length of its diameter";
   - r
    
3. A circular region whose area is indicated by the length of its radius
   "they located it within a radius of 2 miles"
    
4. The outer and slightly shorter of the two bones of the human forearm
   "He fractured his radius in a fall"
    
5. Support consisting of a radial member of a wheel joining the hub to the rim
   "The bicycle's radius was bent in the crash";
   - spoke, wheel spoke

Derived forms: radii, radiuses

Type of: arm bone, length, part, region, straight line, support

Part of: bicycle wheel, cartwheel, diam, diameter, forearm, wagon wheel

Encyclopedia: Radius