A period of two thousand years, or the celebration marking the two-thousandth anniversary of an event.
From Latin bi- (two) + millennium (thousand years). Millennium comes from mille (thousand) + annum (year). The term emerged in modern English to describe major two-thousand-year anniversaries.
The year 2000 was celebrated as a bimillenium event worldwide, but technically it marked 2,000 years since the estimated birth of Jesus—making it one of the most celebrated anniversaries in human history, even though calculating exact years is historically complex.
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