Sulfur oxide refers to many types of sulfur and oxygen containing compounds such as SO, SO₂, SO₃, S₇O₂, S₆O₂, S₂O₂, etc.

Sulfur oxide (SO_x) refers to one or more of the following:

• Lower sulfur oxides (S_nO, S₇O₂ and S₆O₂)
• Sulfur monoxide (SO) and its dimer, Disulfur dioxide (S₂O₂)
• Sulfur dioxide (SO₂)
• Sulfur trioxide (SO₃)
• Higher sulfur oxides (SO₃ and SO₄ and polymeric condensates of them)
• Disulfur monoxide (S₂O)