a colourless oily poisonous liquid with an odour resembling that of geraniums, having a powerful vesicant action and used as a war gas; 1-chloro-2-dichloroarsinoethene. Formula: ClCH:CHAsCl2
Word origin
C20: named after W. L. Lewis (1878–1943), US chemist
lewisite in American English
(ˈluɪsˌaɪt)
US
noun
a pale-yellow, odorless arsenical compound, ClCH=CHAsCl2, used as a blistering poison gas