Sulfur dioxide
WordNet
noun
(1) A colorless toxic gas (SO2) that occurs in the gases from volcanoes; used in many manufacturing processes and present in industrial emissions; causes acid rain
WiktionaryText
Noun
- A toxic gas, of molecular formula SO2 that is found in the emissions of volcanos and those of burning coal or petroleum; dissolves in water to form sulfurous acid and, in the presence of oxygen, sulfuric acid, and is thus responsible for acid rain.