hex·a·chlor·o·ben·zene 
(hĕksə-klôr′ō-bĕnzēn′)
(hĕksə-klôr′ō-bĕnzēn′)n.
A white crystalline benzene derivative, C6Cl6, formerly used as a fungicide to control bunt. Its use in the United States was banned in 1965 due to high toxicity and adverse environmental effects. Also called perchlorobenzene.