Lewisite is a toxic synthetic chemical used as a blister agent in chemical warfare. It is also known as dichloroethyl sulfide and 2-chlorovinyldichloroarsine. Other synonyms include L, L-1, and CD, which were used as code names during World War I and II. The chemical compound is named after the American chemist, Winford Lee Lewis, who invented it in 1918. Lewisite is highly effective in inducing blisters on the skin and respiratory system, and it is extremely toxic to plants and animals. Due to its lethality, Lewisite is banned for use by the Chemical Weapons Convention and the United Nations.