Demi-glace

Demi-glace (English: "half glaze") 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 espagnole sauce, the latter being one of the five mother sauces of classical French cuisine, and the mixture is then simmered and reduced by half.