While adding some softlinks to the WU on St. Dymphna, I glanced at the WUs on Pentecost and found them somewhat wanting. Taking the short topic first:

1. Pentecostal Power

A term used by some evangelical Protestant churches to refer to a perceived overshadowing of the Holy Spirit in a gathering of the faithful. The manifestations of the Holy Spirit, as they are called, are similar to those which took place 50 days after the Resurrection of Jesus on Pentecost among the disciples. They may include shouting, dancing, and speaking in tongues or glossolalia. Worshipers are "set on fire" and may become "slain in the spirit" where they fall over in a swoon. In brief, pentecostal power is the expression of religious enthusiasm which to an unbeliever has all the marks of hysteria.

2. Historical Pentecost

A feast of the Catholic Church, commemorating the Descent of the Holy Spirit upon the Apostles, fifty days after Christ's Resurrection, which took place on the ancient Jewish festival called the "feast of weeks" or Pentecost (Exodus 34:22; Deuteronomy 16:10) (in Hebrew "Shavuoth"). The account of the Christian Pentecost can be found in the 2nd chapter of the Acts, particularly Acts 2:1-4. It is often called Whitsunday, after the white garments ( = Old Eng. hwIta = White)> worn by those who were baptised during the vigil.

Observance of the feast in the very early Church has been attested to by both St. Irenĉus and Tertullian. Various customs for Pentecost have arisen in the countries of Europe to symbolize events of the Feastday. In Italy the tongues of fire that descended on the heads of the Apostles were represented by dropping rose petals from the rafters of the church. In France, the blowing trumpets represented the might wind heard with the descent of the Holy Spirit.

In the Mass from Whitsunday to the following Saturday, the Sequence Veni, Sancte Spiritus is sung:

VENI, Sancte Spiritus, reple tuorum corda fidelium, et tui amoris in eis ignem accende. 
V. Emitte Spiritum tuum et creabuntur; 
R. Et renovabis faciem terrae. 

COME, Holy Spirit, fill the hearts of Thy faithful and kindle in them the fire of Thy love. 
V. Send forth Thy Spirit and they shall be created 
R. And Thou shalt renew the face of the earth. Amen. 

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.

 

© Webster 1913.