lewisitePronunciation: /ˈluːɪsʌɪt/Definition of lewisite noun [mass noun] a dark oily liquid producing an irritant gas that causes blisters, developed for use in chemical warfare. An organic compound of arsenic; chemical formula: ClCHCHAsCl2 Origin: 1920s: named after Winford L. Lewis (1878–1943), American chemistlewisite in other Oxford dictionaries Definition of lewisite in the US English dictionary
