Sulphur dioxide Meaning, Definition & Usage

  1. noun 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
    sulfur dioxide.

WordNet

Definitions
  1. (Chem.), a colorless gas, SO2, of a pungent, suffocating odor, produced by the burning of sulphur. It is employed chiefly in the production of sulphuric acid, and as a reagent in bleaching; called also sulphurous anhydride, and formerly sulphurous acid.

Webster 1913