mousse n.

1892, in cookery sense in reference to a frothy dish stiffened with egg whites, etc., from French mousse, from Old French mousse "froth, scum," from Late Latin mulsa "mead," from Latin mulsum "honey wine, mead," from neuter of mulsus "mixed with honey," related to mel "honey" (from PIE root *melit- "honey"). Meaning "preparation for hair" is from 1977, so called for resemblance of the substance. As a verb in this sense from 1984. Related: Moussed.