An Antiphonary is one of the liturgical books intended for use in choro (i. e. in the liturgical choir), and originally characterized, as its name implies, by the assignment to it principally of the antiphons used in various parts of the Roman liturgy. In current usage Antiphoner refers more narrowly to books containing the chants for the Divine Office in distinction to the Gradual (Graduale or more rarely antiphonarium Missarum), which contains the antiphons used for the Mass.
The discussion below is almost entirely drawn from the 1908 article in the Catholic Encyclopedia. Subsequent developments have been the replacement of the Ratisbon editions with the Vatican edition of 1912 and the publication of the Antiphonale monasticum (1934) produced by the Benedictines of Solesmes, In 1971 the Office was drastically revised and renamed the Liturgy of the Hours (Liturgia Horarum) and new books appeared: the Psalterium monasticum (1981) and the Liber hymnarius (1982).
An Antiphonary may also be called an Antiphonal, Antiphony or Antiphoner. The term comes from the Latin antiphonarium, antiphonarius, antiphonarius liber, antiphonale, which came from the Greek ’antíphonon, antiphon, antiphone, anthem.
It thus included generically the antiphons and antiphonal chants sung by cantor, congregation, and choir at Mass (antiphonarium Missarum, or graduale) and at the canonical Hours ( antiphonarium officii); but now it refers only to the sung portions of the Divine Office or Breviary. Other English equivalents for antiphonary are antiphonar (still in reputable use) and antiphoner (considered obsolete by some English lexicographers, but still sometimes used in current literature). In the "Prioress' Tale" of Chaucer it occurs in the form "antiphonere":