A cappella

A Cappella (Italian: “in the church style”) music is vocal music or singing without instrumental accompaniment, or a piece intended to be performed in this way. A cappella was originally intended to differentiate between Renaissance polyphony and Baroque concertato style. In the 19th century a renewed interest in Renaissance polyphony coupled with an ignorance of the fact that vocal parts were often doubled by instrumentalists led to the term coming to mean unaccompanied vocal music. In modern usage, a cappella often refers to an all-vocal performance of any style, including barbershop, doo wop, and modern pop/rock.
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In church or chapel style; -- said of compositions sung in the old church style, without instrumental accompaniment; as, a mass a capella, i. e., a mass purely vocal.

  

A time indication, equivalent to alla breve.

  

In church [style] i.e. Vocal music only