What does "sulphuryl" mean?

Sulphuryl: The hypothetical radical SO2; -- called also sulphon. Sulphuryl chloride, a chloride, pungent, fuming liquid, SO2.Cl2, obtained by the action of phosphorus pentachloride on sulphur trioxide. On treatment with water it decomposes into sulphuric and hydrochloric acids, and is hence called also sulphuric chloranhydride.