Demiglace is a classic French sauce that is used as a base for many other sauces. If you are looking for synonyms for the word "demiglace", there are a few you can use. One of the most common is "brown sauce", which is a sauce that is made from beef or veal stock, a mirepoix, and a roux. Another synonym is "espagnole sauce", which is similar to demiglace but is made with tomato paste and a brown roux. Finally, "perigueux sauce" is another synonym for demiglace that is made with truffles and Madeira wine. These are all excellent sauces that can be used in a variety of dishes to add flavor and depth.