radius

n. straight line drawn from the center of a circle to the circumference; one of the bones of the forearm

Remote Authentication Dial In User Service (RADIUS) is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. It is intended to work in both local and roaming situations.Many networks services (including corporate networks and public ISPs using modem, DSL, or wireless 802.11 technologies) require you to present security credentials (such as a username and password or security certificate) in order to connect on to the network. Before access to the network is granted, this information is passed to a Network Access Server (NAS) device over the link-layer protocol (for example, Point-to-Point Protocol (PPP) in the case of many dialup or DSL providers), then to a RADIUS server over the RADIUS protocol. The RADIUS server checks that the information is correct using authentication schemes like PAP, CHAP or EAP. If accepted, the server will then indicate to the NAS that you are authorized to access the network. RADIUS also allows the authentication server to supply the NAS with additional parameters, such asThe specific IP address to be assigned to the userThe address pool from which the user's IP should be chosenThe maximum length that the user may remain connectedAn access list, priority queue or other restrictions on a user's accessL2TP parameters
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In classical geometry, a radius (plural: radii) of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment. The radius is half the diameter. In science and engineering the term radius of curvature is commonly used as a synonym for radius.
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Radius /ra·di·us/ pl. ra´dii [L.] 1. a line from the center of a circle to a point on its circumference. 2. [more]Radius - Community and Resources

Noun
1. the length of a line segment between the center and circumference of a circle or sphere
(synonym) r
(hypernym) length
(hyponym) semidiameter
(part-holonym) diameter, diam
2. a straight line from the center to the perimeter of a circle (or from the center to the surface of a sphere)
(hypernym) straight line
3. a circular region whose area is indicated by the length of its radius; "they located it within a radius of 2 miles"
(hypernym) region, part
4. the outer and slightly shorter of the two bones of the human forearm
(hypernym) arm bone
(part-holonym) forearm
5. support consisting of a radial member of a wheel joining the hub to the rim
(synonym) spoke
(hypernym) support
(part-holonym) bicycle wheel

n. radius, straight line drawn from the center of a circle to the circumference; one of the bones of the forearm