Vegetarianism: Having one’s food source be primarily of plant origin, for health, ethical, moral, religious, ecological or economic reasons. There are three types of vegetarians: ovo-lactovegetarians, who do not eat meat but use milk, milk products, and eggs; lactovegetarians, who consume milk products but no meat or eggs; vegans, or pure vegetarians, who avoid all animal foods in any form. (Prentice-Hall Dictionary of Nutrition and Health)