Whit ‧ sun /ˈwɪts ə n/ BrE AmE noun [uncountable and countable] British English
1 . ( also ˌWhit ˈSunday ) the seventh Sunday after Easter, when Christians celebrate the ↑ Holy Spirit coming down from heaven SYN Pentecost
2 . ( also Whit‧sun‧tide /ˈwɪts ə ntaɪd/) the period around Whitsun