Glossary of Terms:

omni off/mono mode

A MIDI device set to this mode will respond only to MIDI data that it receives on its assigned MIDI channel. It will also play only one note at a time.

Source: Yamaha: Sound Reinforcement Handbook

Related terms:   MIDI   omni   omni off/mono mode   omni off/poly mode   omni on/mono mode   omni on/poly mode