1. A beam of light, heat, or other form of radiation. The rays from radium and other radioactive substances are produced by a spontaneous disintegration of the atom; they are electrically charged particles or electromagnetic waves of extremely short wavelength. 2. A part or branch that extends radially from a structure. [L. radius]
- actinic r. a light r. toward and beyond the violet end of the spectrum that acts upon a photographic plate and produces other chemical effects. SYN: chemical r..
- alpha r. SYN: alpha particle.
- anode rays those originating in a gas discharge tube and moving in a direction opposite to that of cathode rays; made up of positively charged ions. SYN: positive rays.
- Becquerel rays obsolete term for radiation given off by uranium and other radioactive substances; these include α, β, and γ rays.
- beta r. SYN: beta particle.
- cathode rays a stream of electrons emitted from the negative electrode (cathode) in a Crookes tube; their bombardment of the anode or the glass wall of the tube gives rise to x-rays.
- chemical r. SYN: actinic r..
- cosmic rays high-velocity particles of enormous energies, bombarding earth from outer space; the “primary radiation” consists of protons and more complex atomic nuclei that, on striking the atmosphere, give rise to neutrons, mesons, and other less energetic “secondary radiation.”
- direct rays SYN: primary rays (2).
- gamma rays electromagnetic radiation emitted from radioactive substances; they are high-energy x-rays but originate from the nucleus rather than the orbital shell and are not deflected by a magnet.
- glass rays those formed by cathode rays striking the wall of an x-r. tube; a special case of indirect rays and soft x-rays. Obsolete.
- grenz r. (grents) very soft x-rays, closely allied to the ultraviolet rays in their wavelength ( i.e., relatively long) and in their biologic action upon tissues; they are produced by a specially built vacuum tube with a hot cathode operating from a transformer delivering not more than 8 kw. [Ger. Grenze, borderline, boundary]
- H rays a stream of hydrogen nuclei; i.e., protons.
- hard rays rays of short wavelength and great penetrability.
- incident r. the r. that strikes the surface before reflection.
- indirect rays x-rays generated at a surface other than the anode target.
- intermediate rays those between ultraviolet and x-rays. SYN: W rays.
- marginal rays in geometric optics, those rays originating from the periphery.
- medullary r. the center of the renal lobule, which has the shape of a small, steep pyramid, consisting of straight tubular parts; these may be either ascending or descending limbs of the nephronic loop or collecting tubules. SYN: Ferrein pyramid, pars radiata lobuli corticalis renis, processus ferreini.
- Niewenglowski rays radiation emitted from a phosphorescent body after exposure to sunlight.
- parallel rays rays parallel to the axis of an optical system.
- paraxial rays in geometric optics, those rays focused at the principal point.
- positive rays SYN: anode rays.
- primary rays 1. cosmic rays in the form in which they first strike the atmosphere; 2. x-rays generated at the focal spot of the tube. SYN: direct rays.
- reflected r. a r. of light or other form of radiant energy which is thrown back from a nonpermeable or nonabsorbing surface; the r. which strikes the surface before reflection is the incident r..
- roentgen r. SYN: x-r. (1).
- secondary rays x-rays generated when primary x-r.'s impinge upon matter; scattered radiation.
- soft rays x-rays of relatively long wavelength and slight penetrability.
- supersonic rays rays with a wavelength higher than that perceptible to the human ear, above 20,000 Hz.
- W rays SYN: intermediate rays.
- x-r. x-r..

* * *

ray 'rā n any of numerous elasmobranch fishes (order Hypotremata) having the body flattened dorsoventrally, the eyes on the upper surface, and a much-reduced caudal region having typically a slender process often with venomous spines
ray n
1) one of the lines of light that appear to radiate from a bright object
2) a beam of radiant energy (as light) of small cross section
3 a) a stream of material particles traveling in the same line (as in radioactive phenomena)
b) a single particle of such a stream
rayed 'rād adj

* * *

(ra) [L. radius spoke] 1. a line emanating from a center. 2. a distinct portion of electromagnetic radiation that proceeds in a specific direction. 3. any of various marine elasmobranch fishes with flattened bodies and narrow tails. See also stingray.

Medical dictionary. 2011.


Look at other dictionaries:

  • ray — ray …   Dictionnaire des rimes

  • RAY — steht für: Ray (Persien), auch Rayy, eine Industriestadt in Iran Ray (North Dakota), USA Ray (Arizona) Ray sur Saône, Gemeinde im französischen Département Haute Saône beim Bookcrossing die Abkürzung für einen Bookray ein österreichisches… …   Deutsch Wikipedia

  • Ray — /ray/ for 1, 2, 4, 5; /ruy/ for 3, n. 1. John, 1627? 1705, English naturalist. 2. Man /man/, 1890 1976, U.S. painter and photographer. 3. Satyajit /sut yeuh jit/, 1921 92, Indian film director. 4. a male given name, form of Raymond …   Universalium

  • Ray — (homonymie)  Pour les articles homophones, voir RE, Ret et Raie (homonymie). Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom. Sommaire …   Wikipédia en Français

  • 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]… …   The Collaborative International Dictionary of English

  • RAY (M.) — Pionnier, avec Marcel Duchamp et Picabia, du mouvement le plus radical de l’art moderne qui, de Dada au surréalisme, traverse jusqu’à notre époque tout le champ des arts visuels, Man Ray a largement contribué, par son œuvre polymorphe: tableaux,… …   Encyclopédie Universelle

  • RAY — Antique cité iranienne au sud est de l’agglomération téhéranaise, près de la ville moderne de Shahr e Rey, Ray (Rayy chez les géographes arabes, ou encore Rey, ou Rai) est située à l’affleurement d’une abondante nappe phréatique. L’occupation du… …   Encyclopédie Universelle

  • Ray — Ray, Man Ray, Nicholas Ray, Satyajit * * * (as used in expressions) Bradbury, Ray (Douglas) Charles, Ray Ray Charles Robinson Delany, Samuel R(ay) Eames, Charles y Ray Leonard, Sugar Ray Ray Charles Leonard Milland, Ray …   Enciclopedia Universal

  • Ray — steht für: Ray (Familienname), einen Familiennamen Ray (Vorname), einen Vornamen Ray (Persien), auch Rayy, eine Industriestadt in Iran Ray (North Dakota), USA Ray (Arizona) Ray (Zeitschrift), ein österreichisches Filmmagazin Ray (Comicserie),… …   Deutsch Wikipedia

  • Ray — Ray, n. [F. raie, L. raia. Cf. {Roach}.] (Zo[ o]l.) (a) Any one of numerous elasmobranch fishes of the order Rai[ae], including the skates, torpedoes, sawfishes, etc. (b) In a restricted sense, any of the broad, flat, narrow tailed species, as… …   The Collaborative International Dictionary of English

  • Ray — Saltar a navegación, búsqueda Ray puede referirse a: Abreviatura científica para el botánico John Ray (1627 1705) Ray Charles, cantante, pianista y artista Ray Bradbury, escritor estadounidense Ray Thompson, creador de la serie de culto La Tribu… …   Wikipedia Español

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”