Liturgical music of the Roman Catholic church consisting of unaccompanied melody sung in unison to Latin words.
It is named for Pope Byzantine chant ) and elsewhere. Chant has traditionally been performed at the mass and the canonical hours (the eight prayer services traditionally held daily in monasteries). Its texts come primarily from the biblical psalms, metrical hymns, and texts specific to the mass and the hours. The melodies are classified as belonging to one or another of the eight church mode s. Chant rhythm is not strictly metrical, and its notation does not indicate rhythm. Since the Second Vatican Council , the performance of chant has diminished greatly. See also {{link=cantus firmus">cantus firmus .