any of the several fat-soluble, antirachitic vitamins D1, D2, D3, 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.
a mixture of lumisterol and calciferol, obtained by ultraviolet irradiation of ergosterol.
a D vitamin, C27H43OH, occurring in fish-liver oils, that differs from vitamin D2 by slight structural differences in the molecule. Also called cholecalciferol.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.