Antiphonary
An Antiphonary, Antiphonal, "Antiphony" or Antiphoner (Latin antiphonarium, antiphonarius, antiphonarius liber, antiphonale; Greek ’antíphonon, antiphon, antiphone, anthem) 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).