Ergocalciferol
![Skeletal formula of ergocalciferol](/Images/godic/202501/31/Ergocalciferol.svg3633.png")
![Ball-and-stick model of the ergocalciferol molecule](/Images/godic/202501/31/Ergocalciferol_3D_ball3633.png")
Ergocalciferol (vitamin D2) is a form of vitamin D. Ergocalciferol is a secosteroid formed by a photochemical bond breaking of a steroid, specifically, by the action of ultraviolet light on ergosterol. Viosterol, the name given to early preparations of irradiated ergosterol, is essentially synonymous with ergocalciferol.