Anniversary days of joy. They are either immovable or movable. The chief immovable feasts are the four rent-days—viz. the Annunciation or Lady-Day (March 25th), the Nativity of John the Baptist (June 24th), Michaelmas Day (September 29th), and Christmas Day (December 25th). The Circumcision (New Year's Day, January 1st), Epiphany (January 6th), All Saints' (November 1st), All Souls' (November 2nd), and the several Apostles' days.
Good Friday. The Friday next before Easter Sunday.
Ash Wednesday. The first day of Lent.
Sexagesima Sunday. Sixty days before Easter Sunday.
Ascension Day or Holy Thursday. Fortieth day after Easter Sunday. Pentecost or Whit-Sunday. The seventh Sunday after Easter Sunday. Trinity Sunday. The Sunday next after Pentecost, etc. etc.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894