An antiphonary or antiphonal 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 Latin liturgical rites.

Medieval antiphonaries varied with regional liturgical tradition. In 1570, following the Council of Trent, the Roman Rite antiphonary was declared universal. The Roman Antiphonary (Antiphonale Romanum) contains the chants for the canonical hours for the hours of Lauds, Prime, Terce, Sext, None, Vespers and Compline for every day of the year. The Vesperale Romanum is an excerpt of the Antiphonary containing the chants sung at Vespers. The music for use at the Mass is contained in the Roman Gradual (Graduale Romanum), the chants of the ordinary are also edited as an excerpt from the Gradual, the Kyriale Romanum. The Antiphonale Romanum was substantially revised in 1910–11 in the course of the reform of the Roman Breviary under Pope Pius X, notably restoring authentic Gregorian melodies. For the 1971 "Liturgy of the Hours", there are two volumes, Antiphonale Romanum II and Liber Hymnarius.

Alternative terms for Antiphonary are Antiphonal or Antiphony. The term comes from the Latin antiphonarium, antiphonarius, antiphonarius liber, antiphonale, which came from the Greek antíphonon "antiphone, anthem".

In current usage, Antiphonary 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 Antiphonary 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 the early 20th century). In the "Prioress' Tale" of Chaucer it occurs in the form antiphonere:

The word Antiphonary had in the earlier Middle Ages sometimes a more general, sometimes a more restricted meaning. In its present meaning it has also been variously and insufficiently defined as a "Collection of antiphons in the notation of Plain Chant", and as a liturgical book containing the antiphons "and other chants". In its present complete form it contains, in plain-chant notation, the music of all the sung portions of the Roman Breviary immediately placed with the texts, with the indications of the manner of singing such portions as have a common melody (such as versicles and responses, the Psalms, the Lessons, the Chapters). But the Lessons of Matins (First Nocturn) in the triduum of Holy Week, styled "Lamentations", have a melody proper to themselves, which is not therefore merely indicated but is placed immediately with the texts of the Lessons.

In order to show as clearly as possible the exact position of the antiphonary amongst the liturgical books, it is proper to recall that the Roman Missal contains all the texts used at Mass; the Roman Breviary, all the texts used in the Divine Office or Canonical Hours. While in the Missal, the introits, graduals, tracts, sequences, offertories, communions, as well as the texts of the Kyrie, Gloria, Credo, Sanctus, and Agnus Dei are both read by the celebrant and sung by the choir, their notation is not given, only the accentus or chants, of the celebrant and deacon have the music furnished (such as the intonations of the Gloria, the Credo, the chants of the various Prefaces, the two forms of the Pater Noster, the various forms of the Ite, or Benedicamus, the Blessing of the Font, etc.). The omitted chants (styled concentus), which are to be sung by the choir, are contained in a supplementary volume called the "Graduale" or "Liber Gradualis" (anciently the "Gradale").