Meaning of AUDIO in English

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.

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.