radii
 (pl.)半徑
 radii
 輻管,輻部,輻射線(解剖),半徑,橈骨,邊花(菊科),傘形花序枝
 Ra·di·i n., pl. of Radius.
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 Ra·di·us n.; pl. L. Radii E. Radiuses
 1. Geom. A right line drawn or extending from the center of a circle to the periphery; the semidiameter of a circle or sphere.
 2. Anat. The preaxial bone of the forearm, or brachium, corresponding to the tibia of the hind limb. See Illust. of Artiodactyla.
 Note: ☞ The radius is on the same side of the limb as the thumb, or pollex, and in man it is so articulated that its lower end is capable of partial rotation about the ulna.
 3. Bot. A ray, or outer floret, of the capitulum of such plants as the sunflower and the daisy. See Ray, 2.
 4. pl. Zool. (a) The barbs of a perfect feather. (b) Radiating organs, or color-markings, of the radiates.
 5. The movable limb of a sextant or other angular instrument.
 Radius bar Mach., 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.
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 radius
      n 1: the length of a line segment between the center and
           circumference of a circle or sphere [syn: r]
      2: a straight line from the center to the perimeter of a circle
         (or from the center to the surface of a sphere)
      3: a circular region whose area is indicated by the length of
         its radius; "they located it within a radius of 2 miles"
      4: the outer and slightly shorter of the two bones of the human
         forearm
      5: support consisting of a radial member of a wheel joining the
         hub to the rim [syn: spoke]
      [also: radii (pl)]
 radii
      See radius