The Collaborative International Dictionary
hyposulphurous acid
Thiosulphuric \Thi`o*sul*phur"ic\, a. [Thio- + sulphuric.] (Chem.) Of, pertaining to, or designating, an unstable acid, H2S2O3, analogous to sulphuric acid, and formerly called hyposulphurous acid.
Wiktionary
hyposulphurous acid
n. (context chemistry English) (alternative spelling of hyposulfurous acid English)