chlo·ro·sulfonic acid \| ̷ ̷ ̷ ̷+...-\noun alsochlor·sulfonic acid\|klōr, -ȯr+\ Etymology:chlor- + sulfonic : a colorless fuming corrosive liquid ClSO3H made usually by reaction of gaseous hydrogen chloride with sulfur trioxide and used chiefly in organic synthesis (as of sulfa drugs, saccharin, and sulfonic acids)