Dioxin may refer to a number of different substances. Most notably:
- 1,2-Dioxin or 1,4-dioxin, two unsaturated heterocyclic 6-membered rings in which two carbon atoms have been replaced by oxygen atoms, which gives the molecular formula C<sub>4</sub>H<sub>4</sub>O<sub>2</sub>. They are unstable.
- Dibenzo-1,4-dioxin, also known as dibenzodioxin or dibenzo-p-dioxin (molecular formula C<sub>12</sub>H<sub>8</sub>O<sub>2</sub>), in which two benzene rings are connected through two oxygen atoms. That is the parent compound of the dioxins (see next in which the dioxins comprise a key part of the class).
- Dioxins and dioxin-like compounds, a diverse class of polychlorinated chemical compounds, including polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs), that are persistent organic pollutants and known to exhibit "dioxin-like" toxicity.
- 2,3,7,8-Tetrachlorodibenzodioxin (TCDD), the prototypical and most toxic example of the above class, often referred to simply as "dioxin".
See also