IPA: //ˌæn.tɪˈfɒn.ər.i//
KK: /æn'tɪfənɛri/
A book that contains a collection of antiphons, which are musical responses sung in a religious service, especially during the Divine Office.
The choir used the antiphonary to follow the musical responses during the service.
Antiphonary → It is formed from "anti-" (meaning against or opposite) and "phōnē" (meaning voice or sound) and the suffix "-ary" (meaning relating to or connected with). The word refers to a book containing antiphons, which are responses sung in opposition to a choir or congregation's voice.
Think of 'anti-' meaning against and 'phōnē' meaning voice — an antiphonary is a book that relates to voices singing in opposition.