antiphon

antiphon , in Roman Catholic liturgical music, generally a short text sung before and after a psalm or canticle. The main use is in group singing of the Divine Office in a monastery. However, the sung introit, offertory, and communion verses of the Mass are also antiphons, whose psalms have for the most part disappeared. Certain festival chants, sung preparatory to the Mass itself, are called antiphons. There are also the four antiphons of the Blessed Virgin Mary, which are in the nature of office hymns and are sung by alternating choirs (i.e., antiphonally), each one belonging to a certain portion of the year. The best known of these is Salve Regina, of whose text there are many polyphonic settings. Modern antiphons are set to composed music rather than plainsong . These are independent choral works for which the English term anthem was derived from antiphon.