I. au ‧ di ‧ o 1 /ˈɔːdiəʊ $ ˈɒːdioʊ/ BrE AmE adjective [only before noun]
[ Date: 1900-2000 ; Origin: audio- 'of hearing' , from Latin audire 'to listen' ]
relating to sound that is recorded or broadcast:
audio and video equipment
II. audio 2 BrE AmE noun [uncountable]
the part of a recording that contains sounds and music but not pictures:
You can save the audio for editing later.