1.  audio(n = noun.communication) sound - the audible part of a transmitted signal; "they always raise the audio for commercials"
is a kind of auditory communication
is a part of telecasting, television, tv, video

2.  audio(n = noun.attribute) audio frequency - an audible acoustic wave frequency;
is a kind of frequence, frequency, oftenness

3.  audio(n = noun.artifact) audio recording, sound recording - a recording of acoustic signals;
is a kind of recording
has particulars: audiotape, disc, disk, phonograph record, phonograph recording, platter, record, soundtrack, talking book

4.  audio(n = noun.artifact) - the sound elements of television;
is a kind of component, constituent, element
is a part of television, television system

1.  the part of a transmitted signal which conveys the sound of the event represented by the signal, such as that of a television program. [WordNet 1.5]

2.  an audible acoustic wave frequency. [WordNet 1.5]

3.  the sound elements of television. [WordNet 1.5]

audio, n. (usu. attrib.) sound or the reproduction of sound.

Idiom:
audio frequency a frequency capable of being perceived by the human ear. audio typist a person who types direct from a recording.

Etymology:
AUDIO-

audio amplifier, audio cd, audio compact disc, audio frequency, audio lingual acquisition, audio recording, audio system