jubilee

noun

1. (Jewish history) A special year of emancipation supposed to be kept every fifty years, when farming was abandoned and Hebrew slaves were set free.
2. A 25th, 40th, 50th, 60th or 70th anniversary.
3. A special year (originally held every hundred years, then fifty, and then fewer) in which remission from sin could be granted as well as indulgences upon making a pilgrimage to Rome.
4. A time of celebration or rejoicing.