Responsory

In music, church chant involving the response by a choir to a verse sung by soloists, also called respond. Originally this would have taken the form of a response by the congregation to the leader or cantor. In the 9th century, it became an elaborate musical form demanding trained soloists and choir. The Gradual, Alleluia, and (for a time) the Offertory of the Mass were responsorial chants.

The most important responsoria in the Offices were the responsoria prolixa, sung at Matins. Like those of the Mass, they became a vehicle for polyphonic settings, the polyphony being reserved for the soloists' portions of the chant. When choral polyphony became the norm in the mid-15th century, the procedure was frequently, though not invariably, reversed. Late 16th-century settings, such as those by Tomás Victoria for Holy Week, assign the entire text to the polyphonic choir.