noun

• The Jewish festival of Shavuot.
• The particular (Jewish) Pentecost 49 days (inclusive) after the resurrection of Jesus on the (Jewish) Day of First Fruits, when (in Christian teaching) the Holy Spirit descended upon the Apostles with miraculous effects including the ability to explain the Gospel intelligibly in languages they did not know; or a similar occasion since.
• The Christian festival (also known as Whitsun or Whitsunday), which commemorates the descent of the Holy Spirit upon the Apostles.
• Pentecostal manifestation, such as in a church service.
• A surname.