The phrase "outer hull" refers to the protective covering or shell that surrounds something, like the outer layer of a ship or the skin of a fruit. It provides protection and helps keep the inside safe from potential harm or damage. Full definition
In the case of both white and brown rice, the inedible outer hull of the rice is removed so that the grain of the rice is accessible. (globalnaturopath.com)
By fresh oats I mean whole oat kernels from a farmer's field similar to other grains you might buy such as whole wheat berries, with only their inedible outer hull removed. (mariaspeck.com)
Brown rice, often referred to as whole rice or cargo rice, is the whole grain with only its inedible outer hull removed. (whfoods.org)