The Collaborative International Dictionary of English v.0.48:

Sulphinic \Sul*phin"ic\, a. (Chem.)
   Of, pertaining to, or designating, any one of a series of
   acids regarded as acid ethereal salts of hyposulphurous acid;
   as, methyl sulphinic acid, CH3.SO.OH, a thick unstable
   liquid.
   [1913 Webster]