Demi glace (also demi-glaze, demi glace) is a rich brown sauce in French cuisine used by itself or as a base for other sauces. The term comes from the French word glace, which used in reference to a sauce means icing or glaze. It is traditionally made by combining equal parts of veal stock and sauce espagnole, the latter being one of the four mother sauces of classical French cuisine, and the mixture is then simmered and reduced by half. Common variants of demi-glace use a 1:1 mixture of beef or chicken stock to sauce espagnole; these are referred to as "beef demi-glace" (demi-glace au boeuf) or "chicken demi-glace" (demi-glace au poulet). The term "demi-glace" by itself implies that it is made with the traditional veal stock.
A very rich and flavorful brown sauce made from reduction of sauce Espagnole with the addition of wine and veal stock. This is a very long procedure and requires constant skimming.
Demiglace is a thick, intensely flavored, glossy brown sauce that is served with meat, poultry, or fish or used as a base for other sauces. It is made by thickening a rich veal stock, enriching it with diced vegetables, tomato paste and Madiera or sherry, then reducing it until concentrated.