What is "whitsunday"

Pentecost \Pen"te*cost\, n. [L. pentecoste, Gr. ? (sc. ?) the fiftieth day, Pentecost, fr. ? fiftieth, fr. ? fifty, fr. ? five. See Five, and cf. Pingster.]

1. A solemn festival of the Jews; -- so called because celebrated on the fiftieth day (seven weeks) after the second day of the Passover (which fell on the sixteenth of the Jewish month Nisan); -- hence called, also, the Feast of Weeks. At this festival an offering of the first fruits of the harvest was made. By the Jews it was generally regarded as commemorative of the gift of the law on the fiftieth day after the departure from Egypt.

2. A festival of the Roman Catholic and other churches in commemoration of the descent of the Holy Spirit on the apostles; which occurred on the day of Pentecost; -- called also Whitsunday.
   --Shak.

Whitsunday \Whit"sun*day\, 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.

2. (Scots Law) See the Note under Term, n., 12.

"Pentecost," late Old English Hwita Sunnandæg "white Sunday" (see white (adj.)); possibly so called from the white baptismal robes worn by newly baptized Christians on this day. Related: Whitsuntide.