A vocal performance with no instrumental accompaniment.
Singing solely or mainly without instrumental accompaniment.
Related to a form of purely vocal music mostly associated with American college performance groups.
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.
The deep roar of a large animal, or any similar loud noise.
To shout in a deep voice.
To make a loud, deep, hollow noise like the roar of an angry bull.