Pentecost (Ancient Greek: πεντηκοστή [ἡμέρα], pentekostē [hēmera], "the fiftieth ay") is one of the prominent feasts in the Christian liturgical year, celebrated the 49th day (7 weeks) after Easter Sunday (the tenth day after Ascension Thursday). Historically and symbolically related to the Jewish harvest festival of Shavuot, it commemorates the descent of the Holy Spirit upon the Apostles and other followers of Jesus as described in the Book of Acts, Chapter 2. Pentecost is also called Whitsun, Whitsunday, or Whit Sunday, especially in the United Kingdom.