duet: [18] The original term for ‘two musicians’ was Italian duo, a descendant of Latin duo ‘two’. English acquired this in the 16th century. But Italian (the major source of Western musical vocabulary) also produced a diminutive form duetto, literally ‘little duo’, which English borrowed either directly (the unanglicized form duetto was used in English for about a hundred years from the 1720s) or perhaps via German duett. => two
1740, from French duet, from Italian duetto "short musical composition for two voices," diminutive of duo "two" (see two). As a verb, from 1822. The Italian form of the noun was used in English from c. 1724.
