A French term that refers to a mixture of flour and a fat, such as cooking oil, margarine, or butter, that is cooked and used for thickening in sauces and gravies. Roux can be cooked to three different stages. If cooked just a few minutes, the mixture, sometimes referred to as a white roux, does not change color and is used to thicken white sauces. Heating the roux a few minutes more gives a golden color. This blond roux is used in lightly colored sauces. A brown roux is formed when the mixture is cooked slowly to a rich brown color. When properly browned, the roux also will have a nutty aroma. A brown roux is used, especially in French and Cajun cooking, to flavor, thicken and color soups, stews, sauces and gumbos.