The Collaborative International Dictionary of English v.0.48:
Jubilee \Ju"bi*lee\, n. [F. jubil['e], L. jubilaeus, Gr. ?, fr.
Heb. y[=o]bel the blast of a trumpet, also the grand
sabbatical year, which was announced by sound of trumpet.]
1. (Jewish Hist.) Every fiftieth year, being the year
following the completion of each seventh sabbath of years,
at which time all the slaves of Hebrew blood were
liberated, and all lands which had been alienated during
the whole period reverted to their former owners. [In this
sense spelled also, in some English Bibles, jubile.]
--Lev. xxv. 8-17.
2. The joyful commemoration held on the fiftieth anniversary
of any event; as, the jubilee of Queen Victoria's reign;
the jubilee of the American Board of Missions.
3. (R. C. Ch.) A church solemnity or ceremony celebrated at
Rome, at stated intervals, originally of one hundred
years, but latterly of twenty-five; a plenary and
extraordinary indulgence granted by the sovereign pontiff
to the universal church. One invariable condition of
granting this indulgence is the confession of sins and
receiving of the eucharist.
4. A season of general joy.
The town was all a jubilee of feasts. --Dryden.
5. A state of joy or exultation. [R.] "In the jubilee of his
spirits." --Sir W. Scott.