A Jubilee

1. (Jewish historical) A special year of emancipation supposed to be kept every fifty years, when farming was abandoned and Hebrew slaves were set free. [from 14th c.]
2. A 25th, 40th, 50th, 60th or 70th anniversary. [from 14th c.]
3. (Catholicism) A special year (originally held every hundred years, then fifty, and then fewer) in which remission from sincould be granted as well as indulgences upon making a pilgrimage to Rome. [from 15th c.] - A time of celebration or rejoicing. [from 16th c.]
4. An occasion of mass manumission from slavery. :
5. (obsolete) A period of fifty years; a half-century. [17th-18th c.]