A collection of chants to be sung antiphonally by the choir in public worship. It is also known as an antiphonal. It originally provided chants for the eucharist and the Daily Offices of the church. The chants for the eucharist and for the Daily Offices were eventually separated. A chant-book for the eucharist is now typically known as a graduale, or book of graduals. An antiphonary or antiphonal typically refers to a chant-book for the Daily Offices.
Glossary definitions provided courtesy of Church Publishing Incorporated, New York, NY,(All Rights reserved) from "An Episcopal Dictionary of the Church, A User Friendly Reference for Episcopalians," Don S. Armentrout and Robert Boak Slocum, editors.