A synthesizer or sampler is multitimbral if it is capable of producing more than one type of sound, or timbre (pronounced TAM-burr), at a time. This is typically described as the number of "parts" a unit can play at once. An example would be playing a keyboard's "piano" patch or preset (i.e. part) and then layering/adding a "string" part, to play a "piano/strings" combination. This would be commonly referred to as a two part/multitimbral situation. A keyboard/sampler that is 16 part/multitimbral will allow you to play up to 16 patches or sounds layered one on top of another. This is distinct from the amount of polyphony, or number of actual notes the unit can simultaneously generate.