noun the barbs of a perfect feather.
2. radius ·noun radiating organs, or color-markings, of the radiates.
3. radius ·noun the movable limb of a sextant or other angular instrument.
4. radius ·noun a ray, or outer floret, of the capitulum of such plants as the sunflower and the daisy. ·see ray, 2.
5. radius ·noun a right line drawn or extending from the center of a circle to the periphery; the semidiameter of a circle or sphere.
6. radius ·noun the preaxial bone of the forearm, or brachium, corresponding to the tibia of the hind limb. ·see ·illust. of artiodactyla.