1. Any sauce to which whipped cream or beaten egg whites have been added just prior to serving to give it a light, airy consistency. Mousseline sauce is hollandaise blended with whipped cream. 2. Various dishes based on meat, fish, shellfish or foie gras (usually pureed) to which whipped cream or, less frequently, beaten egg whites are added to lighten the texture. 3. A term applied to any of various dishes or baked goods that have a light and delicate texture.