annunciation (n.) Look up annunciation at Dictionary.com
early 14c., "Lady-day, Church festival commemorating announcement of the incarnation of Christ," from Anglo-French anunciacioun, Old French anonciacion "announcement, news; Feast of the Annunciation," from Latin annuntiationem (nominative annuntiatio), noun of action from past participle stem of annuntiare "announce, relate" (see announce).

General sense of "an announcing" is from 1560s. The Church festival (March 25) commemorates the visit of the angel Gabriel to the Virgin Mary, foretelling the incarnation. Old English for "Annunciation Day" was bodungdæg.