vitamin D 3

vitamin D3,

an antirachitic, white, odorless crystalline unsaturated alcohol that is the predominant form of vitamin D of animal origin. It is found in most fish-liver oils, butter, brain, and egg yolk and is formed in the skin, fur, and feathers of animals and birds exposed to sunlight or ultraviolet rays. Also called activated 7-dehydrocholesterol, cholecalciferol.