Season of Pentecost

• Period seven weeks after Easter
• The week beginning on Whitsunday (especially the first 3 days)
• Christian holiday

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
late 13c., contraction of Whitsunday .

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Whitsun \Whit"sun\, a. Of, pertaining to, or observed at, Whitsuntide; as, Whitsun week; Whitsun Tuesday; Whitsun pastorals.

Wikipedia Word definitions in Wikipedia
Whitsun (also Whitsunday , Whit Sunday or Whit ) is the name used in Britain and Ireland, and among Anglicans throughout the world, for the Christian festival of Pentecost , the seventh Sunday after Easter , which commemorates the descent of the Holy Spirit ...