[mɪˈlɛnɪəm], (Noun)

Definitions:
- a period of a thousand years, especially when calculated from the traditional date of the birth of Christ
(e.g: silver first came into use on a substantial scale during the 3rd millennium BC)

- an anniversary of a thousand years
(e.g: the millennium of the Russian Orthodox Church)


Phrases:

Origin:
mid 17th century: modern Latin, from Latin mille ‘thousand’, on the pattern of biennium