WordWeb Online

1. Characterized by oppressive heat and humidity
   "the summer was sulphureous and oppressive";
   - sultry, stifling, sulfurous [N. Amer], sulphurous [Brit, Cdn]
    
2. Of or related to or containing sulphur or derived from sulphur
   - sulfurous [N. Amer], sulphurous [Brit, Cdn]
    
3. Harsh or corrosive in tone
   - acerb, acerbic, acid, acrid, bitter, blistering, caustic, sulfurous [N. Amer], sulphurous [Brit, Cdn], virulent, vitriolic, acidulous

See also: hot, unpleasant