found: Grove music online, viewed May 28, 2014 :(In Latin Christian chant generally, a liturgical chant with a prose text, sung in association with a psalm. In Gregorian psalmody, for example, psalms and canticles are usually preceded and followed by a single antiphon, and the psalm tone used for the recitation of the psalm itself is often musically incomplete without the antiphon. Antiphons of this kind may be regarded as typical and are represented above all by the Gregorian antiphons to the psalms of Matins, Lauds and Vespers in the Divine Office. There are also other categories of antiphon, some of which may lack psalmody or have versified texts. The antiphon and responsory are the two musical genres with Latin prose texts that occur in all the Western liturgies and are the most abundant within the chant repertory. A given medieval Office source might have as many as 1500 antiphons, and even up to 2000; such a large number could occur in a monastic usage, whereas the secular (or canons') repertory would generally have fewer)
