2,3,7,8-tetrachlorodibenzo-para-dioxin, 2,3,7,8-tetrachlorooxanthrene, dioxin, 2,3,7,8-TCDD, TCDD
a chemical compound in the form of a chlorinated hydrocarbon which occurs as an impurity in the herbicide 2,4,5-T, is highly toxic and persistent, and is a teratogen, a carcinogenic dioxin C12H4O2Cl4 found especially as a contaminant in 2,4,5-T