What is the definition of vitamins a-e and k?

These are all essent. These are all essential vitamins for every one to survive you can not define these vitamins, as there is no definition as these are all vitamins. Definition of vitamins in general is essential nutrients body can not produce but needs in small amount fir health and development.Vitamins do not supply with energy as some believe, but perform several roles in keeping the body working&protect from diseas.