a period of 1 000 years, especially as calculated before or after the birth of Christ 一千年，千年期（尤指公元纪年） the second millennium AD 公元第二个千年 For millennia, it was accepted that the earth was at the centre of the universe. 几千年来，人们一直认为地球处于宇宙的中心。
- the millennium
the time when one period of 1 000 years ends and another begins 千周年纪念日；千禧年
Word Originmid 17th cent.: modern Latin, from Latin mille ‘thousand’, on the pattern of biennium.