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vitamin D

noun
1.
any of the several fat-soluble, antirachitic vitamins D 1 , D 2 , D 3 , occurring in milk and fish-liver oils, especially cod and halibut, or obtained by irradiating provitamin D with ultraviolet light, essential for the formation of normal bones and teeth.
Origin
1920-1925
1920-25

vitamin D1

noun
1.
a mixture of lumisterol and calciferol, obtained by ultraviolet irradiation of ergosterol.

vitamin D2

noun

vitamin D3

noun
1.
a D vitamin, C 27 H 43 OH, occurring in fish-liver oils, that differs from vitamin D 2 by slight structural differences in the molecule.
Also called cholecalciferol.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for vitamin D

vitamin D

noun (pl) D vitamins
1.
any of the fat-soluble vitamins, including calciferol and cholecalciferol, occurring in fish-liver oils (esp cod-liver oil), milk, butter, and eggs: used in the treatment of rickets and osteomalacia

vitamin D1

noun
1.
the first isolated form of vitamin D, consisting of calciferol and its precursor, lumisterol

vitamin D2

noun
1.
another name for calciferol

vitamin D3

noun
1.
another name for cholecalciferol
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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vitamin D in Medicine

vitamin D n.
A fat-soluble vitamin occurring in several forms, especially vitamin D2 or vitamin D3, required for normal growth of teeth and bones, and produced in general by ultraviolet irradiation of sterols found in milk, fish, and eggs.

vitamin D2 n.
A white crystalline compound produced by ultraviolet irradiation of ergosterol. Also called calciferol, ergocalciferol.

vitamin D3 n.
A colorless crystalline compound found in fish-liver oils, irradiated milk, and all irradiated animal foodstuffs and having biological activity similar to vitamin D2. Also called cholecalciferol.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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vitamin D in Science
vitamin D  
Any of a group of fat-soluble sterols necessary for normal bone growth, especially vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D is found in milk, fish, and eggs and can be produced in the skin on exposure to sunlight. A deficiency of vitamin D in the diet causes rickets in children.
vitamin D2  
A white crystalline sterol produced by ultraviolet irradiation of ergosterol and also occurring naturally in fungi and some fish oils. Vitamin D2 is the form of vitamin D generally used as a dietary supplement. Also called calciferol, ergocalciferol. Chemical formula: C28H44O.
vitamin D3  
A colorless, crystalline steroid hormone that the body synthesizes in the skin when its precursor, a derivative of cholesterol, is irradiated by sunlight. Vitamin D3 is also found in fish-liver oils, irradiated milk, and all irradiated animal foodstuffs. Also called calciferol, cholecalciferol. Chemical formula: C27H44O.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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