Definitions for lady day
Random House Webster's College Dictionary
Ref: annunciation (def. 2). 3
Origin of Lady Day:
Annunciation, Lady Day, Annunciation Day, March 25(noun)
a festival commemorating the announcement of the Incarnation by the angel Gabriel to the Virgin Mary; a quarter day in England, Wales, and Ireland
25th March, an English quarter day.
25th March, Christian holy day, the Annunciation of the Virgin Mary.
The Nuttall Encyclopedia
the festival of the annunciation of the Virgin Mary, March 25; a quarter-day in England and Ireland.