Douglas Harper's Etymology Dictionary
Wikipedia
Usage examples of "walpurgis".
And they were less suspected than if they had met atop Brocken on Walpurgis Night.
Walpurgis revels would be held in the dark ravine beyond Meadow Hill where the old white stone stands in a place queerly devoid of all plant-life.
Norse Walpurgis night celebration was in full roar as they rode up to the settlement.
Adela Chemping, who considered herself in some measure superior to the allurements of an ordinary bargain sale, made a point of attending the reduction week at Walpurgis and Nettlepink's.