A vocal performance with no instrumental accompaniment.
Singing solely or mainly without instrumental accompaniment.
An a cappella group sang during the wedding reception.
Related to a form of purely vocal music mostly associated with American college performance groups.
Alla breve.
In a manner of a choir with no instrumental accompaniment; literally, "in the style of the (Sistine) Chapel (in Rome)", such as a musical Mass done a cappella.
Groups of teens singing a cappella on street corners got recording contracts.
In alla breve time.