What does Lustrum mean?

For the lustrum of the association they organised a whole trip to Barcelona.

Dutch student slang. This is a Dutch word. You will hear it a lot at Dutch universities, student associations and in student houses.

Every five years a Dutch student association celebrates big. Think of a lustrum trip, a lustrum gala and often a whole week of events. Some even celebrate a midlustrum after two and a half years. Any excuse for a party. Also read about dies and dispuut.