A septet is a group of seven people or things, especially seven musicians performing together. When seven violinists, or a mix of seven different instruments, play as a unit, they form a septet. Jazz musicians might form a septet with trumpet, saxophone, trombone, piano, guitar, bass, and drums. Classical composers have written beautiful pieces for string septets or wind septets.

You might also use septet to describe seven singers performing together, or even seven of anything grouped as a unit: a septet of planets, a septet of novels in a series, or seven friends who always hang out together.

In music, septets create an interesting challenge. They're large enough to produce a rich, full sound with many different musical voices, but small enough that each musician's individual part matters enormously. Unlike an orchestra, where several people might play the same part, in a septet each performer typically plays a unique role that contributes something essential to the whole.