n (context|Roman Catholicism) A psalm sung or chanted immediately before the collect, epistle, and gospel, and while the priest is entering within the rails of the altar, which begins with this verse: «Requiem aeternam dona eis, Domine».
n (context|Roman Catholicism) A part of a psalm or other portion of Scripture read by the priest at Mass immediately after ascending to the altar.
n An anthem or psalm sung before the Communion service.
n Any composition of vocal music appropriate to the opening of church services.