acapella

Around 1600, Italian musicians and theorists began noting that the most solemn liturgical music in the great papal chapels was performed without organ or strings. They called this practice a cappella, meaning in the manner of the chapel. The phrase captured something the Italians found both austere and ennobling about unaccompanied voices filling a vaulted nave.

The phrase traces to the Italian word cappella, meaning chapel or choir. That word descended from Medieval Latin capella, which first referred to the short cloak of Saint Martin of Tours, preserved as a relic by Frankish kings in the fourth century. The portable shrine housing the relic was also called capella, and over centuries the word transferred to the stone building, then to the choir that sang within it.

English borrowed a cappella from Italian music treatises in the 1860s, at first as a specialist term among choral directors reviving Renaissance polyphony. Victorian choral societies in England and Germany needed a name for the unaccompanied tradition they were celebrating, and Italian supplied the readiest one. The phrase entered general use steadily across the nineteenth century.

By the twentieth century, a cappella had broken free of its liturgical origins entirely. Barbershop quartets, doo-wop groups on American street corners in the 1950s, and later collegiate singing ensembles adopted the word to describe any vocal performance without instruments. The spelling acapella, stripped of its Italian spacing, is the form that stuck in common English use.