Fumet is the French term for concentrates stock of fish, meat, mushroom, or game reduced with wine until concentrated that is used as a flavoring in French cooking. It is a strong stock usually applied to fish.
Moreover, fumet, refers to an aromatic broth made for use in soups and sauces. The flavor of a fumet is usually concentrated on one item, though multiple ingredients may be used. The stock is then reduced to concentrate this flavor. Fish and vegetable broths are more commonly called fumets, but meat may also be used.