vitamin D n. Any of several chemically related fat-soluble vitamins that prevent rickets. It is found in fish-liver oils, egg yolks and milk. Component vitamin D2 is also called calciferol, and vitamin D3 is called cholecalciferol.
... nature of which is unknown) and the oil of the liver of cod (or less expensive fish) exposed to the beneficial rays of ultraviolet light—artificial sunlight—to imbue the oil with an extra large and uniform dose of vitamin D? The ancients, it appears, knew "vitamin D" to exist. Maybe they had a different name for "vitamins," maybe none at all. The name does not matter. The thing which they knew, does. They knew the nutritive ... — Cooking and Dining in Imperial Rome • Apicius
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