Masa means "dough" in Spanish, but in Mexico it is generally understood as "corn dough." For some, masa is to Mexican cooking what stock can be to French, the defining and essential element. It is made by boiling corn kernels in powdered lime (calcium oxide), washing them and then grinding. Enough water is then mixed into the meal to make a dough. Smoother, soft masa is required for tortillas, and coarser, stiff masa is used for tamales.