moussen.[F.]1. (Cookery) A frozen dessert of a frothy texture, made of sweetened and flavored whipped cream, sometimes with the addition of egg yolks and gelatin. Mousse differs from ice cream in being beaten before -- not during -- the freezing process.()2. Any of a variety of foods whipped to a light texture; as, a salmon mousse.()3. A foam containing special chemicals, used for styling hair.()