The term "grain flour" refers to a type of flour that is made from grinding grains into a fine powder. This powder can then be used as a substitute for traditional wheat flour in many recipes, making it an excellent option for those with gluten intolerance or sensitivity. Some common types of grain flours include rice flour, oat flour, and cornmeal. These flours are often used to make baked goods such as breads, cakes, and cookies that are free from wheat-based ingredients.