A cappella : 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 cappella : A time indication, equivalent to alla breve.

Example:


Taxonomy
a cappella, instruments, musical instruments, instrumental music, music, cappella music, the New Testament, Christians, the church, God, Collegiate a cappella, song, Musical Instruments of the Bible, New Testament, cappella groups, Jewish, Articles with unsourced statements, United States.

Defination from the web:
A cappella was originally intended to differentiate between Renaissance polyphony and Baroque concertato style. ... Gregorian chant is an example of a cappella singing, as is the majority of sacred vocal music from the Renaissance. ...