vitamin - any of a group of organic substances essential in small quantities to normal metabolism

antiophthalmic factor, axerophthol, vitamin A, A - any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes

calciferol, cholecarciferol, D, ergocalciferol, viosterol, vitamin D - a fat-soluble vitamin that prevents rickets

E, tocopherol, vitamin E - a fat-soluble vitamin that is essential for normal reproduction; an important antioxidant that neutralizes free radicals in the body

antihemorrhagic factor, naphthoquinone, vitamin K - a fat-soluble vitamin that helps in the clotting of blood