instrumentation
particular combination of musical instruments employed in a composition
duet
musical composition or arrangement for two performers
septet
musical composition for seven voices or instruments
quintet
musical composition for five voices or instruments
quartet
musical composition for four voices or instruments
solo
musical piece or part of musical piece performed by a single musician; musical performance by a single voice, musician or instrument
nonet
composition which requires nine musicians for a performance
orchestration
the musical art of composing or arranging works for orchestra