Shavuot

Culture/religion: Judaism
Date: May 17-18
Shavuot is a two-day holiday celebrating the completion of the seven-week Omer counting period between Passover and Shavuot.
The Torah was given by God to the Jewish people on Shavuot, and every year on the holiday the acceptance of God’s gift is renewed.
In observance of Shavuot, candles are lit on the first and second evening of the holiday; it is customary to stay up all night learning Torah on the first night; people go to the synagogue on the first day to hear a reading of the Ten Commandments; special meals are eaten and no work may be performed.
Shavuot begins the evening of May 16. Work is not permitted May 16-18.
Alternate spelling: Shavu’ot
Pronunciation: shuh-VOO-oht / shah-VOO-uhs
Sources:
What is Shavuot (Shavuos)?, Chabad.org
Glossary of Jewish Terminology, Judaism 101, jewfaq.org
Declaration of the Báb

Culture/religion: Bahá’í
Date: May 23
Declaration of the Báb commemorates the day the Báb, the herald of the Bahá’í faith announced that he was the new messenger of God. The day is one of the nine holy days when work is suspended.
Bahá’ís celebrate through prayers and retelling the story of the declaration.
Pronunciation: Bahá’í: Ba-HIGH; Báb: Bahb (Bob)
Sources:
Declaration of the Báb, Bahá’ís of the United States
Declaration of the Báb, The Bahá’í Faith Portland/Vancouver Metro Area Community;
Style guide, glossary and pronunciation guide, Bahá’í World News Service
Pentecost

Culture/religion: Christianity
Date: May 23
Always occurring 50 days after the death and resurrection of Jesus and ten days after his ascension into heaven, Christians observe Pentecost to remember when the Holy Spirit descended on the apostles, causing them to speak in tongues.
Pentecost is considered to be the birthday of the Church, as it is when Peter, the first Pope, preaches for the first time and converts thousands of new believers.
Pentecost is celebrated in various ways around the world – wearing red vestments as a symbol of the burning fire of God’s love and the tongues of fire that descended on the apostles; white vestments worn in Britain and Ireland for “WhitSunday” or “White Sunday” as a symbol of the dove of the Holy Spirit; the Italian tradition of scattering rose leaves from the ceiling of the churches to recall the miracle of the fiery tongues, Pentecost sometimes being called Pascha Rosatum (Easter roses); blowing trumpets during Mass in France to recall the sound of the driving wind of the Holy Spirit; reciting long poems and prayers during an extra service in Asia; and carrying flowers or green branches during services in Russia.
Pentecost shares roots with the Jewish holiday of Shavuot which is the celebration of the beginning of the early weeks of the wheat harvest.
Sources:
Everything you need to know about Pentecost, Catholic News Agency
Pentecost is this Sunday. What the heck is Pentecost?, PBS.org