A Cappella Definition

ä kə-pĕlə
adverb
Without instrumental accompaniment.
American Heritage

(music) 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.[First attested in the late 19th century.]

Groups of teens singing a cappella on street corners got recording contracts.
Wiktionary
adjective
Without instrumental accompaniment.
Webster's New World
(music) Singing solely or mainly without instrumental accompaniment.[First attested in the late 19th century.]
An a cappella group sang during the wedding reception.
Wiktionary
Synonyms:

Other Word Forms of A Cappella

Noun

Singular:
a cappella
Plural:
a cappellas

Origin of A Cappella

  • From Italian alla cappella (“in the manner of the [Sistine] chapel”), referring to non-instrumental choirs; from Latin a-, ad, "to", + cappella, "chapel".

    From Wiktionary

  • Italian a in the manner of cappella chapel, choir

    From American Heritage Dictionary of the English Language, 5th Edition