'antiphonary' originates from Medieval Latin, specifically the word 'antiphonarium', where 'antiphona' (from Greek 'antiphōnē') meant 'responsive song' (from anti- 'opposite/alternate' + phōnē 'voice').

'antiphonary' changed from Medieval Latin 'antiphonarium' (and Old French/Anglo-Norman forms such as 'antifonaire'/'antiphonaire') and eventually became the modern English word 'antiphonary' through Middle English adaptations.

Initially, it meant 'a collection of antiphons' (songs or responses for liturgical use), and over time it has retained this specialized meaning referring to the liturgical book.