jubilee

1. A special year of emancipation supposed to be observed every fifty years, when farming was temporarily stopped, certain houses and land which had been sold could be redeemed by the original owners or their relatives, and Hebrew slaves set free. (countable)
2. A special year (originally held every hundred years, then at more frequent intervals, and now declarable by the Pope at any time and also for periods less than a year) in which plenary indulgences and remission from sin can be granted upon making a pilgrimage to Rome or other designated churches. (countable, uncountable)
3. A major anniversary of an event, particularly the fiftieth (50th) anniversary of a coronation or marriage. (countable, uncountable)
4. A time for release or restitution. (countable, figuratively)
5. A time of celebration or rejoicing. (countable, figuratively)
6. Exultation, rejoicing; jubilation. (figuratively, uncountable)
7. The sound of celebration or rejoicing; shouts of joy. (figuratively, uncountable)
8. A joyful African-American (usually Christian) folk song. (countable, figuratively)

Plural jubilees