Skip to definition.
Get the FREE one-click dictionary software for Windows or the iPhone/iPad and Android apps


Noun: radius (radii,radiuses)  rey-dee-us
  1. The length of a line segment between the centre and circumference of a circle or sphere
    - r
     
  2. A straight line from the centre to the perimeter of a circle (or from the centre to the surface of a sphere)
     
  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
     
  5. Support consisting of a radial member of a wheel joining the hub to the rim
    - 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