In music, a decet—sometimes dectet, decimette, or even tentet (Gerhart 2005)—is a composition which requires ten musicians for a performance, or a musical group that consists of ten people. The corresponding German word is Dezett, the French is dixtuor. Unlike some other musical ensembles such as the string quartet, there is no established or standard set of instruments in a decet.
Of the ensemble types named according to the number of musicians in the group, the decet and the larger undecet, duodecet, etc., are names less common in music than smaller groupings. In the eighteenth century, ten-part ensembles were most often encountered in the genre of the wind serenade, or divertimento (for example, Mozart, K. 186 & 166, both for 2 oboes, 2 clarinets, 2 English horns, 2 horns, and 2 bassoons). Because the wind-serenade tradition was carried on during the 19th century primarily in France, the term dixtuor is somewhat more widely used in French than is its English equivalent, and French works figure most prominently in this ten-instrument configuration—most commonly the double wind quintet. One of the earliest examples to use the English term is the Decet for oboe, clarinet, horn, bassoon, piano, 2 violins, viola, cello, and contrabass (ca. 1841) by John Henry Griesbach (1798–1875) (Bashford 2001). Perhaps the best-known work in this genre from the nineteenth century is Joachim Raff’s Sinfonietta for ten winds, op. 188.