From Longman Dictionary of Contemporary Englishseptetsep‧tet /sepˈtet/ noun [countable] 1 APMa group of seven singers or musicians who perform together2 APMa piece of music written for seven performers
Examples from the Corpus
septet• The band began as an octet, but spent most of the set in various sub-divisions, from quartet through to septet.Origin septet (1800-1900) German Latin septem “seven” 