hyposulphuric

from The Century Dictionary.

• Same as hyposulphurous.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Chem.) Pertaining to, or containing, sulphur in a lower state of oxidation than in the sulphuric compounds.
• adjective an acid, H2S2O6, obtained by the action of manganese dioxide on sulphur dioxide, and known only in a watery solution and in its salts; -- called also dithionic acid. See Dithionic.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Alternative form of hyposulfuric.