Dictionary
vitamin D
any of the several fat-soluble, antirachitic vitamins D
1, D
2, D
3, occurring in milk and fish-liver oils, esp. cod and halibut, or obtained by irradiating provitamin D with ultraviolet light, essential for the formation of normal bones and teeth.
vitamin D1,
a mixture of lumisterol and calciferol, obtained by ultraviolet irradiation of ergosterol.
vitamin D2,
calciferol.
vitamin D3,
a D vitamin, C
27H
43OH, occurring in fish-liver oils, that differs from vitamin D
2 by slight structural differences in the molecule. Also called
cholecalciferol. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.