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4 definitions found
 for Roentgen ray
From The Collaborative International Dictionary of English v.0.48 :

  Ray \Ray\, n. [OF. rai, F. rais, fr. L. radius a beam or ray,
     staff, rod, spoke of a wheel. Cf. Radius.]
     1. One of a number of lines or parts diverging from a common
        point or center, like the radii of a circle; as, a star of
        six rays.
        [1913 Webster]
  
     2. (Bot.) A radiating part of a flower or plant; the marginal
        florets of a compound flower, as an aster or a sunflower;
        one of the pedicels of an umbel or other circular flower
        cluster; radius. See Radius.
        [1913 Webster]
  
     3. (Zool.)
        (a) One of the radiating spines, or cartilages, supporting
            the fins of fishes.
        (b) One of the spheromeres of a radiate, especially one of
            the arms of a starfish or an ophiuran.
            [1913 Webster]
  
     4. (Physics)
        (a) A line of light or heat proceeding from a radiant or
            reflecting point; a single element of light or heat
            propagated continuously; as, a solar ray; a polarized
            ray.
        (b) One of the component elements of the total radiation
            from a body; any definite or limited portion of the
            spectrum; as, the red ray; the violet ray. See Illust.
            under Light.
            [1913 Webster]
  
     5. Sight; perception; vision; -- from an old theory of
        vision, that sight was something which proceeded from the
        eye to the object seen.
        [1913 Webster]
  
              All eyes direct their rays
              On him, and crowds turn coxcombs as they gaze.
                                                    --Pope.
        [1913 Webster]
  
     6. (Geom.) One of a system of diverging lines passing through
        a point, and regarded as extending indefinitely in both
        directions. See Half-ray.
        [1913 Webster]
  
     Bundle of rays. (Geom.) See Pencil of rays, below.
  
     Extraordinary ray (Opt.), that one of two parts of a ray
        divided by double refraction which does not follow the
        ordinary law of refraction.
  
     Ordinary ray (Opt.) that one of the two parts of a ray
        divided by double refraction which follows the usual or
        ordinary law of refraction.
  
     Pencil of rays (Geom.), a definite system of rays.
  
     Ray flower, or Ray floret (Bot.), one of the marginal
        flowers of the capitulum in such composite plants as the
        aster, goldenrod, daisy, and sunflower. They have an
        elongated, strap-shaped corolla, while the corollas of the
        disk flowers are tubular and five-lobed.
  
     Ray point (Geom.), the common point of a pencil of rays.
  
     Roentgen ray, R["o]ntgen ray (r[~e]nt"g[e^]n r[=a]`)
        (Phys.), a form of electromagnetic radiation generated in
        a very highly exhausted vacuum tube by an electrical
        discharge; now more commonly called X-ray. It is
        composed of electromagnetic radiation of wavelength
        shorter than that of ultraviolet light but longer than
        that of gamma rays. It is capable of passing through many
        bodies opaque to light, and producing photographic and
        fluorescent effects by which means pictures showing the
        internal structure of opaque objects are made, called
        X-rays, radiographs, sciagraphs, X-ray photographs,
        radiograms. So called from the discoverer, W. C.
        R["o]ntgen.
  
     X ray, the R["o]ntgen ray; -- so called by its discoverer
        because of its enigmatical character, x being an algebraic
        symbol for an unknown quantity.
        [1913 Webster +PJC]

From The Collaborative International Dictionary of English v.0.48 :

  Roentgen ray \Roentgen ray\
     the Anglicised spelling of R["o]ntgen ray. Same as X ray.
     [PJC]

From The Collaborative International Dictionary of English v.0.48 :

  Rontgen ray \R["o]ntgen ray\, Roentgen ray \Roentgen ray\ [see
     R["o]ntgen.] (Physics)
     An X-ray; originally, the term was applied to any of the
     rays produced when cathode rays strike upon surface of a
     solid (as the wall of the vacuum tube), but now it refers
     specifically to electromagnetic radiation having wavelengths
     from 10^{-3 nm to 10 nm, immediately below ultraviolet
     radiation on the wavelength scale. R["o]ntgen rays are noted
     for their penetration of opaque substances, as wood and
     flesh, their action on photographic plates, and their
     fluorescent effects. They were called X rays by their
     discoverer, W. K. R["o]ntgen. They are one of the forms of
     ionizing radiation, which can have damaging effects on living
     cells. They also ionize gases, but cannot be reflected, or
     polarized, or deflected by a magnetic field. They are used in
     examining opaque objects, especially in medicine for
     visualizing organs and other objects inside the human body,
     as for locating fractures or bullets, and examining internal
     organs for abnormalities.
     [Webster 1913 Suppl. +PJC]

From WordNet (r) 3.0 (2006) :

  roentgen ray
      n 1: electromagnetic radiation of short wavelength produced when
           high-speed electrons strike a solid target [syn: X ray,
           X-ray, X-radiation, roentgen ray]

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