Definition of: requiem

(rē′kwē·əm, rek′wē-) noun
1. Any musical hymn, composition, or service for the dead.
2. Often cap. Eccl. In the Roman Catholic Church, a solemn mass sung for the repose of the souls of the dead, the Requiem mass.
3. Often cap. A musical setting for such a mass; also a similar piece of music using different words. [<L Requiem (aeternam dona eis, Domine) rest (eternal give unto them, O Lord), the opening words of the introit of this mass]