Share on Facebook Share on Twitter Email
Answers.com

gray

 
Dictionary: gray1  grey (grā) pronunciation
 
also adj., gray·er also grey·er, gray·est grey·est.
  1. Of or relating to an achromatic color of any lightness between the extremes of black and white.
    1. Dull or dark: a gray, rainy afternoon.
    2. Lacking in cheer; gloomy: a gray mood.
    1. Having gray hair; hoary.
    2. Old or venerable.
  2. Intermediate in character or position, as with regard to a subjective matter: the gray area between their differing opinions on the film's morality.
n.
  1. An achromatic color of any lightness between the extremes of black and white.
  2. An object or animal of the color gray.
  3. often Gray
    1. A member of the Confederate Army in the Civil War.
    2. The Confederate Army.

v., grayed also greyed, gray·ing grey·ing, grays greys.

v.tr.

To make gray.

v.intr.
  1. To become gray.
    1. To become old; age.
    2. To include a large or increasing proportion of older people: “Federal food programs can't keep up with the nation's rapidly graying population” (Michael J. McCarthy).

[Middle English grei, from Old English grǣg.]

grayly gray'ly adj.
grayness gray'ness n.
gray2 (grā) pronunciation
n. (Abbr. Gy)

The SI unit for the energy absorbed from ionizing radiation, equal to one joule per kilogram.

[After Louis Harold Gray (1905–1965), British radiobiologist.]


Search unanswered questions...
Enter a word or phrase...
All Community Q&A Reference topics
 

Symbol Gy. The derived SI unit of absorbed dose of ionizing radiation (see radiation units). It is named after the British radiobiologist L. H. Gray (1905–65).



 
Idioms: gray
Top
 

[Etymology: L. H. Gray; UK 1905-65] radiation physics. Symbol Gy. SI The derived unit for absorbed dose of ionizing radiation, specific energy imparted, kerma, absorbed dose index, being energy imparted to a dosed material per unit mass, identically J·kg-1 (= m2·s-2 in base terms). Hence
Gy·s-1 for absorbed dose rate.Though the effect of any radiation depends on its amount of energy, it also depends on the type of radiation and on the energy levels of particular particles. The effect on biological tissue depends on the type of tissue and other factors; the unit applying to the net effect is the sievert. The sievert is dimensionally identical with the gray, but the two are distinct as regards context, i.e. the gray should be used only for absorbed dose, the sievert only for dose equivalent. Otherwise, it is accepted that the gray can be used, within the field of ionizing radiations, with other physical quantities also expressed in joules per kilogram.

The gray was defined only by the 15th CGPM of 1975, to succeed the rad as the measure of absorbed dose; 1 Gy = 100 rad.

197515th CGPM: re ionizing radiations ‘adopts the following special name for the SI unit of ionizing radiation: gray, symbol Gy, equal to one joule per kilogram.
Note. - The gray is the SI unit of absorbed dose. In the field of ionizing radiation the gray may also be used with other physical quantities also expressed in joules per kilogram.’see note below

[Le Système International d'Unités (Sèvres, France: Bureau International de Poids et Mesures, 1985)]

 
Gardener's Dictionary: Gray, Asa
Top
(1810–1888)

The leading American botanist of the 19th century. As professor of natural history at Harvard from 1842, he taught many who became eminent botanists, and he popularized the subject through his articles and textbooks.

 
Word Tutor: gray
Top
pronunciation

IN BRIEF: A neutral color midway between white and black.

pronunciation Don't think of gray in your hair, Think of the fun you had putting it there. — Anne Greenwood.

Tutor's tip: Note: "Gray" and "grey" are words that mean the shade between black and white. "Greige" is cotton or silk before dyeing. "Gres" is ceramic stoneware.

 
Wikipedia: Gray (unit)
Top

The gray (symbol: Gy) is the SI unit of absorbed radiation dose due to ionizing radiation (for example, X-rays).

Contents

Definition

One gray is the absorption of one joule of energy, in the form of ionizing radiation, by one kilogram of matter.

1 \ \mathrm{Gy} = 1\ \frac{\mathrm{J}}{\mathrm{kg}} = 1\ \mathrm{m}^2\cdot\mathrm{s}^{-2}

For X-rays and gamma rays, these are the same units as the sievert (Sv). To avoid any risk of confusion between the absorbed dose and the equivalent dose, one must use the corresponding special units, namely the gray instead of the joule per kilogram for absorbed dose and the sievert instead of the joule per kilogram for the dose equivalent.

This SI unit is named after Louis Harold Gray. As with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is uppercase (Gy). When an SI unit is spelled out in English, it should always begin with a lowercase letter (gray), except where any word would be capitalized, such as at the beginning of a sentence or in capitalized material such as a title. Note that "degree Celsius" conforms to this rule because the "d" is lowercase.

Based on The International System of Units, section 5.2.

Origin

The gray was defined in 1975 in honour of Louis Harold Gray (1905–1965), who used a similar concept, "that amount of neutron radiation which produces an increment of energy in unit volume of tissue equal to the increment of energy produced in unit volume of water by one röntgen of radiation," in 1940.

Explanation

The gray measures the deposited energy of radiation. The biological effects vary by the type and energy of the radiation and the organism and tissues involved. The sievert attempts to account for these variations. A whole-body exposure to 5 or more grays of high-energy radiation at one time usually leads to death within 14 days (see Radiation poisoning for details). This dosage represents 375 joules for a 75 kg adult (equivalent to the chemical energy in 20 mg of sugar). Since grays are such large amounts of radiation, medical use of radiation is typically measured in milligrays (mGy).

The average radiation dose from an abdominal x-ray is 1.4 mGy, that from an abdominal CT scan is 8.0 mGy, that from a pelvic CT scan is 25 mGy, and that from a selective spiral CT scan of the abdomen and the pelvis is 30 mGy.[1]

Conversions

One gray is equivalent to 100 rad.

The röntgen is defined as the radiation exposure equal to the quantity of ionizing radiation that will produce one esu of electricity in one cubic centimetre of dry air at 0 °C and a standard atmosphere, and is conventionally taken to be worth 0.258 mC/kg (using a conventional air density of about 1.293 kg/m3). Using an air ionisation energy of about 36.161 J/C, we have 1 Gy ≈ 115 R.

SI multiples for gray (Gy)
Submultiples Multiples
Value Symbol Name Value Symbol Name
10–1 Gy dGy decigray 101 Gy daGy decagray
10–2 Gy cGy centigray 102 Gy hGy hectogray
10–3 Gy mGy milligray 103 Gy kGy kilogray
10–6 Gy µGy microgray 106 Gy MGy megagray
10–9 Gy nGy nanogray 109 Gy GGy gigagray
10–12 Gy pGy picogray 1012 Gy TGy teragray
10–15 Gy fGy femtogray 1015 Gy PGy petagray
10–18 Gy aGy attogray 1018 Gy EGy exagray
10–21 Gy zGy zeptogray 1021 Gy ZGy zettagray
10–24 Gy yGy yoctogray 1024 Gy YGy yottagray
Common multiples are in bold face.

References

  1. ^ Baden, Jeffrey M.; Jay B. Brodsky (1985). The Pregnant surgical patient. London: Futura. ISBN 0-87993-238-4. 

 
Translations: Grey
Top

Dansk (Danish)
adj. - grå, gråhåret, ældet
n. - gråt, ubleget stof el. garn
v. tr. - male grå
v. intr. - blive grå, gråne, ældes

idioms:

  • grey area    gråt område, økonomisk tilbagestillet område
  • grey matter    hjerneceller, grå substans

Nederlands (Dutch)
grijs, grauw, somber, anoniem, saai, grauw licht, schimmel (paard), grijze kleding, grijs maken, vergrijzen

Français (French)
adj. - gris, grisonnant, morne (une vie), terne (un caractère) (péj)
n. - gris, cheval gris
v. tr. - vieillir, grisonner
v. intr. - vieillir, grisonner

idioms:

  • grey area    zone floue
  • grey matter    matière grise

Deutsch (German)
adj. - grau, gesichtslos
n. - Grau, Schimmel
v. - ergrauen

idioms:

  • grey area    Grauzone
  • grey matter    graue Substanz, graue Zellen

Ελληνική (Greek)
adj. - φαιός, γκρίζος, γκρι, σταχτής, ψαρός, (μτφ.) μουντός, σκοτεινός
n. - γκρι, γκρίζο, γκρίζα ρούχα, (άλογο) ψαρής, μουντό φως
v. - (για μαλλιά) γκριζάρω

idioms:

  • grey area    γκρίζα περιοχή/ζώνη, περιοχή με υψηλό ποσοστό ανεργίας
  • grey matter    φαιά ουσία (του εγκεφάλου)

Italiano (Italian)
incanutire, cavallo grigio, grigio

idioms:

  • grey area    poco chiaro
  • grey matter    materia grigia

Português (Portuguese)
adj. - cinza, sombrio, grisalho, maduro
n. - cor (f) cinza, traje (m) cinzento, pano (m) cru
v. - acinzentar, tornar grisalho

idioms:

  • grey area    área (f) nebulosa, área (f) onde o desemprego é alto
  • grey matter    massa (f) cinzenta (Anat.), inteligência (f) (fig.)

Русский (Russian)
серый цвет, серый, седой, мрачный

idioms:

  • grey area    нечто среднее, "серая зона"
  • grey matter    серое вещество головного мозга, умственные способности

Español (Spanish)
adj. - gris, cano, crudo, nublado, triste, oscuro, aburrido, relativo a la vejez o ancianidad
n. - caballo blanco, rucio, gris (color), cualquier cosa de ese color
v. tr. - encanecer, envejecer, ponerse cano, volver de color gris
v. intr. - encanecer, envejecer, ponerse cano, triste, volver de color gris

idioms:

  • grey area    zona gris, terreno poco definido, zona intermedia
  • grey matter    materia gris, seso

Svenska (Swedish)
adj. - grå, grånad, kulen, dyster
n. - grått, grå färg, dämpat ljus, grålle
v. - göra grå, bli grå

中文(简体)(Chinese (Simplified))
灰色的, 阴沉的, 灰色, 使成为灰色, 使变老, 成为灰色或灰白, 发生人口老化

idioms:

  • grey area    灰色区, 指介于两个对立面之间的范畴
  • grey matter    灰白质, 头脑, 智力

中文(繁體)(Chinese (Traditional))
adj. - 灰色的, 陰沈的
n. - 灰色
v. tr. - 使成為灰色, 使變老
v. intr. - 成為灰色或灰白, 發生人口老化

idioms:

  • grey area    灰色區, 指介於兩個對立面之間的範疇
  • grey matter    灰白質, 頭腦, 智力

한국어 (Korean)
adj. - 회색의, 노년의, 우중충한, 암울한, 경험 많은
n. - 회색, 회색 군복, 중년 남자, 회색의 것
v. tr. - 백발이 되게 하다, 회색으로 만들다, 광택을 없애다
v. intr. - 회색이 되다, 백발이 되다

日本語 (Japanese)
adj. - 灰色, 灰色になる, つや消しにする, 葦毛の馬, 灰色の, 青い, 曇った, うす暗い, 白髪まじりの

idioms:

  • grey area    灰色地帯
  • grey matter    灰白質, 頭脳

العربيه (Arabic)
‏(صفه) رمادي, أشيب (الاسم) اللون الرمادي (فعل) يجعله رماديا‏

עברית (Hebrew)
adj. - ‮אפור, קודר, דהה, מדוכא, מדכא, ששערו אפור‬
n. - ‮צבע אפור, חומר אפור או בגדים אפורים, אור שמש חיוור, סוס אפור או לבן‬
v. tr. - ‮עשה לאפור‬
v. intr. - ‮האפיר‬


 
Best of the Web: gray
Top

Some good "gray" pages on the web:


American Sign Language
commtechlab.msu.edu
 
 
 

 

Copyrights:

Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
Chemistry Dictionary. A Dictionary of Chemistry. Sixth Edition. Copyright © Market House Books Ltd, 2008. All rights reserved.  Read more
Idioms. The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Company. All rights reserved.  Read more
Measures and Units. A Dictionary of Weights, Measures, and Units. Copyright © Donald Fenna 2002, 2004. All rights reserved.  Read more
Gardener's Dictionary. Taylor's Dictionary for Gardeners, by Frances Tenenbaum. Copyright © 1997 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.  Read more
Word Tutor. Copyright © 2004-present by eSpindle Learning, a 501(c) nonprofit organization. All rights reserved.
eSpindle provides personalized spelling and vocabulary tutoring online; free trial Read more
Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Gray (unit)" Read more
Translations. Copyright © 2007, WizCom Technologies Ltd. All rights reserved.  Read more