[1] : The Collaborative International Dictionary of English v.0.48

radii \ra"dii\ r=a"di^imac, n.,
   pl. of radius.
   1913 webster
see also:
radius 

[2] : The Collaborative International Dictionary of English v.0.48

radius \ra"dius\ r=a"di^u^s, n.; pl. l. radii
   r=a"di^imac; e. radiuses
   r=a"di^u^se^z. l., a staff, rod, spoke of a
   wheel, radius, ray. see ray a divergent line.
   1. geom. a right line drawn or extending from the center of
      a circle to the periphery; the semidiameter of a circle or
      sphere.
      1913 webster

   2. anat. the preaxial bone of the forearm, or brachium,
      corresponding to the tibia of the hind limb. see illust.
      of artiodactyla.
      1913 webster

   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.
         1913 webster

   3. bot. a ray, or outer floret, of the capitulum of such
      plants as the sunflower and the daisy. see ray, 2.
      1913 webster

   4. pl. zool.
      a the barbs of a perfect feather.
      b radiating organs, or color-markings, of the radiates.
          1913 webster

   5. the movable limb of a sextant or other angular instrument.
      --knight.
      1913 webster

   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.
      1913 webster
see also:
radii radiuses ray artiodactyla radius bar radius of curvature 
curvature 

[3] : WordNet (r) 2.0

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
see also:
r spoke radii 

[4] : WordNet (r) 2.0

radii
     see radius
see also:
radius 

Radii >> R Words
Radii, definition of term: Radii
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