Pentecost means the period of fifty days from the Pasch [Passover] to Pentecost; in the singular it signifies the fiftieth day after the Pasch, or the day of Pentecost itself. Pentecost means fiftieth (day) . It was one of the three great feasts which all males among the Jews were obliged [required] to celebrate in Jerusalem. It lasted but one day, on which they offered to God bread made from the grain of the new harvest and some sacrifices. Cf. Exodus 23:16; Leviticus 23:15; Numbers 33:26; Deuteronomy 16:9.
Our Lord had compared the action of the Holy Ghost to a wind (John 3:8), and in the Old Testament wind often symbolized the presence of God (2 Samuel 5:24; 1 Kings 19:11). At our Lord’s baptism the Holy Spirit appeared in the form of a dove; at the Transfiguration, in the form of a bright cloud; and here, as a fire, to purify, warm, and enlighten the Apostles. The Apostles were moved, therefore, not only by the sound, but also by the appearance, under the form of fire, of God’s Holy Spirit; and this fire had the semblance of tongues, like a candle flame, which settled down on each one of them. The tongues appeared parted, perhaps because each tongue had the appearance of being split as it rested on the head of the Apostles; or because, while the fire was whole in itself, it separated into different shafts or rays of light, as it rested on each of the Apostles. They were all filled with the Holy Ghost which signifies the abundance of the gifts of the Holy Spirit which the Apostles received. Liturgically we use the colour RED to depict this powerful experience.
Whitsunday (also Whitsun, Whit Sunday or Whit) is the name used in the United Kingdom, Ireland and The Caribbean for the Christian festival of Pentecost, the eighth Sunday after Easter Sunday, which commemorates the descent of the Holy Spirit upon Christ's disciples (Acts of the Apostles chapter 2).The name is a contraction of "White Sunday" as WHITE vestments were traditionally worn at baptism to signify purity and movement from darkness to light once the Holy Spirit descended on the individual.