halo·genBrE/ˈhælədʒən/NAmE/ˈhælədʒən/noun (chemistry化学) anyofasetoffivechemicalelements, includingfluorine, chlorine and iodine, that react with hydrogentoformacidsfromwhichsimplesaltscanbemade. Halogens, intheformofgas, areusedinlampsandcookers/stoves卤素