Abbreviation for monophonic.
(1) Capable of producing only one note at a time. A clarinet is monophonic. A bagpipe or an organ is polyphonic.
(2) An audio signal that is carried by a single channel. The number of microphones or loudspeakers that are used to generate and replay the sound is irrelevant; what counts is that the various signals are mixed to one channel. See monaural, stereo.