Glossary of Terms:

omni off/poly mode

A MIDI device set to this mode will respond only to MIDI data that is receives on its assigned MIDI channel. It will also play multiple simultaneous notes, up to its designed polyphonic limit.

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