Biscuit (also known as bisque) refers to any pottery that has been fired in a kiln without a ceramic glaze. This can be a final product such as biscuit porcelain or unglazed earthenware (such as terracotta) or, most commonly, an intermediate stage in a glazed final product.
Bibliography
“Biscuit (Pottery).” 2022. Wikipedia, August. https://en.wikipedia.org/w/index.php?title=Biscuit_(pottery)&oldid=1104101079.