Although it is not wrong to say that those who eat a plant-based diet exclusively have a "vegan diet," veganism, properly used, involves not using animals for food, clothing, entertainment, experiments, teaching, or any other purpose. That is, as the term is properly used, it is necessarily a term describing a moral theory. I should also say that I personally have never met anyone who had a plant-based diet for reasons other than morality who was not a "flexitarian" who consumed animal products at least occasionally. I do not regard a flexitarian diet as a "vegan diet."