The word "a cappella" means singing without any musical instruments. It refers to vocal music that is performed solely using the voices of the singers. Full definition
I doubt Anna Kendrick, Rebel Wilson, Elizabeth Banks and the rest of the cast and crew, when they made the original «Pitch Perfect», were thinking that a comedy about a college A cappella singing group would turn into a viable franchise. (lights-camera-jackson.com)
Pitch Perfect: Sing - Along ACA - Awesome Edition (Blu - ray + Ultraviolet) Release date: May 5 Details: 2012, Universal Studios Home Entertainment Rated: PG - 13, language, sexual content, drug references, crude humor The lowdown: Anna Kendrick and Rebel Wilson star in this comedy about a college a cappella singing group. (thefilmyap.com)
The retreat will conclude with a concert by Canticum Scholare, a professional a cappella ensemble based in New York City that specializes in vocal music of the Renaissance and Baroque. (firstthings.com)