- Walpurgis night
- 1822, from German Walpurgisnacht, witches' revel, especially on Brocken, on May-day eve, literally "the night of (St.) Walpurgis," from Walburga, English abbess who migrated to Heidenheim, Germany, and died there c.780; May 1 being the day of the removal of her bones from Heidenheim to Eichstädt.