From Longman Dictionary of Contemporary EnglishWhitsunWhit‧sun /ˈwɪtsən/ noun [countable, uncountable] British English 1 (also Whit Sunday)TMCRRC the seventh Sunday after Easter, when Christians celebrate the Holy Spirit coming down from heaven SYN Pentecost2 (also Whitsuntide /ˈwɪtsəntaɪd/)TMC the period around Whitsun
Examples from the Corpus
Whitsun• He arrived at Saintes while Richard thought he was still celebrating Whitsun at Poitiers and took the city gates by storm.• At its Whitsun Conference, therefore, the Socialist League unanimously passed the decision to dissolve itself.• A knighthood next Whitsun, and we can sort out the job you want next week.• On the Thursday of Whitsun week, nine villagers from Halling and Snodland were caught and reported for playing tennis.• I used to go and spend Whitsun with an aunt who lived in Sheringham on the coast of Norfolk.• The Whitsun visitors would follow the Easter ones; in no time at all the hotels would be jammed to the doors. 