'annunciatory' originates from Latin, specifically the verb 'annuntiare' (to announce), where 'ad-'/an- meant 'to, toward' and 'nuntiare' (from 'nuntius') meant 'to report, announce'.

'annuntiare' passed into Late Latin as 'annuntiare' and Medieval Latin forms such as 'annuntiatorius', which influenced Middle English/early modern English formations (e.g. 'annunciacion' / 'annunciatory'), eventually yielding the modern English adjective 'annunciatory'.

Initially associated with the act of announcing or reporting ('to announce'); over time it developed as an adjective meaning 'serving to announce' and acquired a specialized liturgical sense 'of the Annunciation'.