radius (ra'de-us). 1

A ray of light, heat, or the like. 2. The semidiameter of a circle or of a sphere. 3. That bone of the forearm which, when the forearm is supinated, lies laterally. It articulates with the ulna and humerus above and with the ulna and carpus below, auricular radii. Lines at right angles to a line pa ing through the auricular points. medullary radii. The bundles of straight uriniferous tubules originating from one main trunk and extending from the medullary nearly to the surface of the cortical portion of the kidney, r. fix us. A line drawn from the inion to the punctum alae vomer is. radii lent is. Lines radiating from the poles of the crystalline lens, which indicate the sutures of the fibers or the points where the ends of these fibers meet. [Lat., radius, rod, staff.]