What is "sulfur trioxide"

alt. (context inorganic compound English) A corrosive liquid, SO₃, which forms sulfuric acid on contact with water; made commercially by the oxidation of sulfur dioxide. n. (context inorganic compound English) A corrosive liquid, SO₃, which forms sulfuric acid on contact with water; made commercially by the oxidation of sulfur dioxide.

Sulfur trioxide (alternative spelling sulphur trioxide) is the chemical compound with the formula SO. In the gaseous form, this species is a significant pollutant, being the primary agent in acid rain. It is prepared on an industrial scale as a precursor to sulfuric acid.