Final answer:
The term for low fired, opaque, nonvitreous ceramic ware is 'earthenware'. Earthenware is less dense and more porous than porcelain or stoneware, and it is often glazed.
Step-by-step explanation:
The term used for low fired, opaque, nonvitreous ceramic ware is earthenware. Unlike porcelain, which is known for its high firing temperature and translucence, or stoneware, which is vitreous and more durable, earthenware is fired at lower temperatures and is less dense, making it more porous. It is often glazed to prevent it from being too permeable. Bone china, another type of ceramic, is made from bone ash and is translucent and very fine, but is not typically considered low fired or nonvitreous.