The word 'Millennium' refers -

• The word 'Millennium' refers to - 1000 years.

• Millennium (noun)
English Meaning: a period of 1,000 years, or the time when a period of 1,000 years ends.
Bangla Meaning: সহস্রাব্দ; বর্ষসহস্রক।

Example Sentence:
- In 2015 the city of Leipzig, Germany, celebrated its millennium.

Source:
1. Cambridge Dictionary.
2. Accessible Dictionary by Bangla Academy.