DuckCorp Dico

Found one definition

1.                 From en.wiktionary.org:
                   
   
   
                   
                     
   [so2]
   
   ** English
   
   *** Noun
   [head=SO <sub> 2 </sub>]
   
    1. [en]  [blood oxygenation] .
   **** Related terms
   
    - [mul]  [molecular oxygen]
    - [en]
    - [en]
    - [en]
   *** See also
   
    - [lang=en]