dioxin

noun4

1. •
   Any of a broad range of toxic or carcinogenic halogenated polycyclic compounds that occur as byproducts of herbicides.

   • The detection of dioxin (specifically, the 2,3,7,8-tetrachlorodibenzo-pdioxin TCDD) in 2,4,5-T raised the question whether dioxin might be present in other herbicides. — 1974
2. •
   The compound 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; molecular formula C₁₂H₄Cl₄O₂), a persistent organic pollutant of the environment which is generally produced as a byproduct of organic synthesis or when organic materials are burned.
3. •
   The parent compound dibenzo-1,4-dioxin or dibenzo-p-dioxin (molecular formula C₁₂H₈O₂), in which two benzene rings are connected through two oxygen atoms; dibenzodioxin, oxanthrene.
4. •
   The unsaturated six-membered heterocycle having four carbon atoms, two oxygen atoms, and two double bonds (molecular formula C₄H₄O₂); 1,2-dioxin and 1,4-dioxin.