\Sul*phon"ic\, a. (Chem.)
Pertaining to, or derived from, a sulphone; -- used
specifically to designate any one of a series of acids
(regarded as acid ethereal salts of sulphurous acid) obtained
by the oxidation of the mercaptans, or by treating sulphuric
acid with certain aromatic bases (as benzene); as, phenyl
sulphonic acid, {C6H5.SO2.OH}, a stable colorless crystalline
substance.
{Sulphonic group} (Chem.), the hypothetical radical,
   {SO2.OH}, the characteristic residue of sulphonic acids.