Dithionic \Di`thi*on"ic\, a. [Pref. di- + -thionic.]

(Chem.) Containing two equivalents of sulphur; as, dithionic acid.

Dithionic acid (Chem.), an unstable substance, H2S2O6, known only in its solutions, and in certain well-defined salts.

Source: Webster's Revised Unabridged Dictionary (1913)