Source : Webster's Revised Unabridged Dictionary (1913)

Sulphurous \Sul"phur*ous\, a. [L. sulphurosus, sulfurosus: cf.
   F. sulfureux.]
   1. Of or pertaining to sulphur.

   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.

   {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}.

Source : WordNet®

sulphurous
     adj 1: harsh or corrosive in tone; "an acerbic tone piercing
            otherwise flowery prose"; "a barrage of acid
            comments"; "her acrid remarks make her many enemies";
            "bitter words"; "blistering criticism"; "caustic jokes
            about political assassination, talk-show hosts and
            medical ethics"; "a sulfurous denunciation" [syn: {acerb},
             {acerbic}, {acid}, {acrid}, {bitter}, {blistering}, {caustic},
             {sulfurous}, {venomous}, {virulent}, {vitriolic}]
     2: characterized by oppressive heat and humidity; "the summer
        was sultry and oppressive"; "the stifling atmosphere";
        "the sulfurous atmosphere preceding a thunderstorm" [syn:
        {sultry}, {stifling}, {sulfurous}]