in Roman Catholic (Roman Catholicism) liturgical music, chant melody and text sung before and after a psalm verse, originally by alternating choirs (antiphonal singing). The antiphonal singing of psalms was adopted from Hebrew worship by the early Christian churches, notably that of Syria, and was introduced into the West in the 4th century by St. Ambrose. The two choirs both sang the psalm text or, alternatively, one choir sang a short refrain between the psalm verses (V) sung by the other choir. The refrain was called an antiphon (A). The resulting musical form was A V₁ A V₂… A. Actually, most of the presentations of the antiphon were in abbreviated form. The antiphon text normally referred to the meaning of the feast day or the psalm. Canticles from the New or Old Testament might also be sung in this way.

Antiphons are now found principally in the canonical hours, or divine office. The parts of the mass known as the introit, offertory, and communion originally consisted of antiphons and psalm verses. During the late Middle Ages the psalm verses were dropped from the offertory and communion, which now consist only of an antiphon. The introit was shortened to one psalm verse and an antiphon (A V A). Musically, the several thousand extant antiphons can be reduced to a small number of melodic types of simple structure. The old antiphonal method of performance was eventually abandoned, and responsorial singing—by a soloist or soloists and a choir—became the norm.

The four Marian antiphons are long hymns, not true antiphons but independent compositions especially noted for their beauty: the “Salve Regina” (“Hail, Holy Queen”), “Ave Regina caelorum” (“Hail, Queen of Heaven”), “Regina caeli, laetare” (“Queen of Heaven, Rejoice”), and “Alma Redemptoris Mater” (“Kindly Mother of the Redeemer”). They were frequently set polyphonically (in part music) by composers from about 1400 onward. There are also special “antiphons” used for processionals at certain high feasts.