a. [ L. sulphurosus, sulfurosus: cf. F. sulfureux. ] 1. Of or pertaining to sulphur. [ 1913 Webster ]

2. (Chem.) (a) Derived from, or containing, sulphur; specifically, designating those compounds in which the element has a lower valence as contrasted with the sulphuric compounds. (b) Having the characteristic odor of sulphur dioxide, or of hydrogen sulphide, or of other sulphur compounds. [ 1913 Webster ]

Sulphurous acid. (a) Sulphur dioxide. See under Sulphur. [ Obs. ] (b) An acid, H2SO3, not known in the free state except as a solution of sulphur dioxide in water, but forming a well-known series of salts (the sulphites). --
Sulphurous anhydride (Chem.), sulphur dioxide. See under Sulphur. [ 1913 Webster ]