معنی کلمه Millennium

a period of 1,000 years, or the time when a period of 1,000 years ends:
The corpse had lain preserved in the soil for almost two millennia.

More examples

The book is a history of the last two millennia.
Imagine what the world will be like at the end of the next millennium.

I will seed a millennium of wisdom ...
This is a new millennium.