Radius n. : A right line drawn or extending from the center of a circle to the periphery; the semidiameter of a circle or sphere.

Radius n. : The preaxial bone of the forearm, or brachium, corresponding to the tibia of the hind limb. See Illust. of Artiodactyla.

Radius n. : A ray, or outer floret, of the capitulum of such plants as the sunflower and the daisy. See Ray, 2.

Radius n. : The barbs of a perfect feather.

Radius n. : Radiating organs, or color-markings, of the radiates.

Radius n. : The movable limb of a sextant or other angular instrument.

Example:
What is the Radius of two cicles with one Radius longer than the other one?

Taxonomy
RADIUS, RADIUS server, RADIUS Accounting, RFC, Accounting, realms, the user, Acct, Attribute, Authorization, RADIUS Authentication, credentials, MIB, network access, server, RADIUS Attributes, authentication, IPv6.

Defination from the web:
RADIUS protocol it is often used by ISPs and enterprises to manage access to the ... RADIUS is a client/server protocol that runs in the application layer, using UDP as transport. ...