Mousse \Mousse\ (m[=oo]s), n. [F.]

(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.

Source: Webster's Revised Unabridged Dictionary (1913)