/ ˌsiː es ˈgæs; NAmE / noun
[ U ] a gas that stings the eyes, producing tears and making it difficult to breathe. CS gas is sometimes used to control crowds.
—see also tear gas
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WORD ORIGIN
1960s: from the initials of Ben B. Corson (1896–1987) and Roger W. Stoughton (1906–57), the American chemists who discovered the properties of the chemical in 1928.