When discussing musical instruments, the ability to play more than one note simultaneously. All instruments have a finite number of notes they can produce at one time. For example, a six string guitar has a maximum of 6-note polyphony. A synthesizer might be 32-note polyphonic, and so on. The more notes of polyphony an instrument can produce, the more capable it is of playing complex arrangements and chords. If the polyphony of the instrument is exceeded, it must “steal” the notes it needs from others that are already sounding. For example, a synthesizer might steal the last note requested from the first one hit; the first note stops, and the new one begins to sound. Some synths and samplers use sophisticated algorithms for voice stealing, others allow you to pre-allocate a given number of voices to a particular MIDI channel, and so on. Compare “polyphonic” to “multitimbral” in the WFTD archive.