What is "x ray"

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.

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.

3. (Zo["o]l.)

   1. One of the radiating spines, or cartilages, supporting the fins of fishes.

   2. One of the spheromeres of a radiate, especially one of the arms of a starfish or an ophiuran.

4. (Physics)

   1. 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.

   2. 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.

5. Sight; perception; vision; -- from an old theory of vision, that sight was something which proceeded from the eye to the object seen.

   All eyes direct their rays On him, and crowds turn coxcombs as they gaze.
   --Pope.

6. (Geom.) One of a system of diverging lines passing through a point, and regarded as extending indefinitely in both directions. See Half-ray.

   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.

   R["o]ntgen ray (r[~e]nt"g[e^]n r[=a]`) (Phys.), a kind of ray generated in a very highly exhausted vacuum tube by the electrical discharge; now more commonly called X-ray. It is composed of electromagnetic radiation of wavelength shorter than that of ultraviolet light, and 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 radiographs, sciagraphs, X-ray photographs, radiograms, or X-rays. 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.

X ray \X ray\, X-ray \X-ray\([e^]ks"r[=a]`), v. t. to examine by means of X-rays; to irradiate with X-rays.

X ray \X ray\, X-ray \X-ray\([e^]ks"r[=a]`), n. [so called by its discoverer because of its enigmatical character, x being an algebraic symbol for an unknown quantity.] (Physics) originally, any of the rays produced when cathode rays strike upon surface of a solid (as a copper target or the wall of the vacuum tube); now defined as electromagnetic radiation with a wavelength of 0.1 to 10 nanometers. X-rays are noted for their penetration of many 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, but were also referred to for some time as Roentgen rays. The term X-ray has become the most common designation. They also ionize gases, but cannot be reflected, or polarized, or deflected by a magnetic field. They are used in examining objects opaque to visible light, as for imaging bones or other structures inside the human body, and for detecting flaws in metal objects, such as in welds.