Molasses, also called treacle, dark brown viscous liquid obtained as a by-product in the processing of sugar, especially cane sugar. Molasses contains uncrystallized sugar and some sucrose. It is used in making industrial alcohol, for cooking, and for feeding stock. Several varieties of molasses, such as New Orleans molasses and Puerto Rico molasses, which are high in sugar content, rich in flavor, and light in color, are used as table syrups.