D defs.my
Entry 5 senses Webster, 1913

Radius

/(rā"dĭ*ŭs)/ · Ra·di·us · IPA /ˈɹeɪ.di.əs/
01 n. A right line drawn or extending from the center of a circle to the periphery; the semidiameter of a circle or sphere.
pl. Radii, Radiuses ((rā"dĭ*ī))
  1. 1.
    A right line drawn or extending from the center of a circle to the periphery; the semidiameter of a circle or sphere.(Geom.)
  2. 2.
    The preaxial bone of the forearm, or brachium, corresponding to the tibia of the hind limb. See Illust. of Artiodactyla.(Anat.) See: Artiodactyla
  3. 3.
    A ray, or outer floret, of the capitulum of such plants as the sunflower and the daisy. See Ray, 2.(Bot.) See: Ray
  4. 4.
    The barbs of a perfect feather.(Zool.)
  5. 5.
    The movable limb of a sextant or other angular instrument.
Phrases & compounds
Radius bar — a bar pivoted at one end, about which it swings, and having its other end attached to a piece which it causes to move in a circular arc.
Radius of curvature — See under Curvature.