what is the meaning of sulpher dioxide???

【化】二氧化硫

Sulfur dioxide (also sulphur dioxide) is the chemical compound with the formula SO2. This important gas is the main product from the combustion of sulfur compounds and is of significant environmental concern. SO2 is often described as the "smell of burning sulfur."
SO2 is produced by volcanoes and in various industrial processes. Since coal and petroleum contain various amounts of sulfur compounds, their combustion generates sulfur dioxide. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid rain.[
http://en.wikipedia.org/wiki/Sulfur_dioxide

sulphur dioxide 是一個gas， chemical formula SO2.
佢係一種colorless gas。佢係acidic when dissolved in water