os os /ˈɑːs/

noun

1. () A mouth or mouthlike opening  ( os )
   a mouth or mouthlike opening
   
2. Rigid connective tissue that makes up the skeleton of vertebrates  ( os , bone )
   rigid connective tissue that makes up the skeleton of vertebrates
    The human body is made up of 206 bones
   The human body is made up of 206 bones
   
   

 OS

1. The left eye  ( oculus sinister , OS )
   the left eye
   
2. (computing) software that controls the execution of computer programs and may provide various services  ( operating system , OS )
   (computing) software that controls the execution of computer programs and may provide various services
   
   

 Os

1. A hard brittle blue-grey or blue-black metallic element that is one of the platinum metals; the heaviest metal known  ( atomic number 76 , Os , osmium )
   a hard brittle blue-grey or blue-black metallic element that is one of the platinum metals; the heaviest metal known