/ muːs; NAmE / noun [ C , U ]
1.
a cold dessert (= a sweet dish) made with cream and egg whites and flavoured with fruit, chocolate, etc.; a similar dish flavoured with fish, vegetables, etc. :
a chocolate / strawberry mousse
salmon / mushroom mousse
2.
a substance that is sold in aerosols , for example the light white substance that is used on hair to give it a particular style or to improve its condition
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WORD ORIGIN
mid 19th cent.: from French , moss or froth .