whitsunday

n. [ White + Sunday. ] 1. (Eccl.) The seventh Sunday, and the fiftieth day, after Easter; a festival of the church in commemoration of the descent of the Holy Spirit on the day of Pentecost; Pentecost; -- so called, it is said, because, in the primitive church, those who had been newly baptized appeared at church between Easter and Pentecost in white garments. [ 1913 Webster ]

2. (Scots Law) See the Note under Term, n., 12. [ 1913 Webster ]