radius

views updated May 14 2018

ra·di·us / ˈrādēəs/ • n. (pl. ra·di·i / ˈrādēˌī/ or ra·di·us·es) 1. a straight line from the center to the circumference of a circle or sphere. ∎ a radial line from the focus to any point of a curve. ∎ the length of the radius of a circle or sphere. ∎ a specified distance from a center in all directions: there are plenty of local pubs within a two-mile radius.2. Anat. the thicker and shorter of the two bones in the human forearm. Compare with ulna. ∎ Zool. the corresponding bone in a vertebrate's foreleg or a bird's wing. ∎ Zool. (in an echinoderm or coelenterate) any of the primary axes of radial symmetry. ∎ Entomol. any of the main veins in an insect's wing.

radius

The Oxford Pocket Dictionary of Current English

radius

views updated May 17 2018

radius (in anatomy) The smaller of the two bones in the lower section of the forelimb of a tetrapod vertebrate (compare ulna). The radius articulates with some carpal bones and the ulna at the wrist and with the humerus at the elbow. This sophisticated articulation of the radius enables humans (and some other animals) to twist the forearm (see pronation; supination).

A Dictionary of Biology

RADIUS

views updated May 29 2018

RADIUS Acronym for Remote Access Dial-In User Service. A protocol for transmitting authentication requests and responses and associated accounting records across an IP network. RADIUS is frequently used by Internet Service Providers to carry login requests from a modem or other network access device to a central user authentication database. RADIUS is not itself an authentication protocol, but supports a wide range of different authentication methods.

A Dictionary of Computing JOHN DAINTITH

radius

views updated May 08 2018

radius In tetrapods, the bone of the fore limb on the side of the first digit (in humans, the thumb). Compare ULNA.

A Dictionary of Earth Sciences AILSA ALLABY and MICHAEL ALLABY

radius

views updated May 23 2018

radius (ray-di-ŭs) n. the outer and shorter bone of the forearm (compare ulna). It partially revolves about the ulna, permitting pronation and supination of the hand.
—radial adj.

A Dictionary of Nursing

radius

views updated May 29 2018

radius In anatomy, one of the two forearm bones, extending from the elbow to the wrist. The radius rotates around the ulna, permitting the hand to rotate and be flexible.

World Encyclopedia

radius

views updated Jun 27 2018

radius †staff of a cross XVI; thicker and shorter bone of the forearm; straight line drawn from the centre of a circle to the circumference XVII; (techn.) rod, bar, ray XVIII. — L. radius staff, spoke, ray, radius of a circle, of the arm, etc.

The Concise Oxford Dictionary of English Etymology T. F. HOAD

RADIUS

views updated Jun 08 2018

RADIUS (ˈreɪdɪəs) Religious Drama Society of Great Britain

The Oxford Dictionary of Abbreviations FRAN ALEXANDER , PETER BLAIR , JOHN DAINTITH , ALICE GRANDISON , VALERIE ILLINGWORTH , ELIZABETH MARTIN , ANNE STIBBS , JUDY PEARSALL , and SARA TULLOCH