Pentecost means "the fiftieth day ". Since ancient times it has been the Feast of Weeks, a feast in the ancient Israel calendar. It celebrates the giving of the Law to Moses. It is called Shavuot.

This was borrowed by the Christians as a feast marking the descent of the Holy Spirit upon the120 Apostles and other followers of Jesus Christ as told in the Acts of the Apostles 2:1–31. It is often called the "Birthday of the Church".

The feast is also called Whitsun, being fifty days after Easter Sunday.