Dominica In Albis
From BiblePortal Wikipedia
Dominica In Albis [1]
(the Sunday of white garments), a title anciently given to the Sunday after Easter, because on this day those persons who had been baptized at Easter appeared for the last time in the chrysomes, or white robes, which they received at baptism. These were laid up in the church as evidences of their baptismal profession. — Bingham, Orig. Ecclesiastes book 20, chapter 5, § 12.