The term 'GRAIN USED AS FOOD' can be summarized as 'CEREAL', which is a type of grain that is commonly used as food. CEREAL grains are the most widely consumed staple food in the world, and are a major source of nutrition for people around the world. CEREAL grains are usually milled into flour, which is then used to make bread, pasta, and other foods. CEREAL grains are also used to make breakfast cereals, which are popular among children and adults alike.