mil·​len·​ni·​um | \ mə-ˈle-nē-əm How to pronounce millennium (audio) \
plural millennia\ mə-​ˈle-​nē-​ə How to pronounce millennium (audio) \ or millenniums

Definition of millennium

1a : the thousand years mentioned in Revelation (see revelation sense 3) 20 during which holiness is to prevail and Christ is to reign on earth
b : a period of great happiness or human perfection
2a : a period of 1000 years especially : one reckoned from the beginning of the Christian era at the start of the third millennium
b : a 1000th anniversary or its celebration In 2015 the city of Leipzig, Germany, celebrated its millennium.

Did you know?

Since in Latin mille means "thousand", a millennium lasts 1,000 years. Thus, we're living today at the beginning of the third millennium since the birth of Christ. But some religious sects, relying on a prophecy in the biblical Book of Revelation, speak of a coming millennium when Jesus will return to reign on earth for 1,000 years, evil will be banished, and all will live in peace and happiness. Members of these sects who keep themselves in a constant state of preparedness are called millenarians or millennialists.

Examples of millennium in a Sentence

The book describes the changes that have occurred in the landscape over many millennia. The year 2000 was celebrated as the beginning of the third millennium.
Recent Examples on the Web By the start of the new millennium, new art became an asset class, traded like stocks or real estate. Los Angeles Times, 17 Dec. 2021 At the beginning of the new millennium, American Psycho confirmed a truth that would only seem truer in the ensuing years: that even when a wealthy New York businessman does the absolute worst, he still won’t be held accountable. Alison Willmore, Vulture, 6 Dec. 2021 By the turn of the new millennium, the item was widely considered an eyebrow-raising sartorial mishap. CNN, 15 Nov. 2021 The James Webb Space Telescope—the top flagship recommendation of the first Decadal Survey of the new millennium—is only now reaching the launchpad after a series of near-catastrophic multibillion-dollar budget overruns and agonizing schedule slips. Lee Billings, Scientific American, 4 Nov. 2021 The five-bottle set comprises cask-strength samples from the 182-year-old distillery that range from the 1960s through to the new millennium. Viju Mathew, Robb Report, 8 Oct. 2021 This summer, when a once-in-a-millennium heat wave enveloped the Pacific Northwest, shattering high-temperature records and ending hundreds of lives, people in neighborhoods with scant tree cover suffered the most. James Ross Gardner, The New Yorker, 29 Nov. 2021 The big tech companies founded around the turn of the millennium would not exist without it. Noam Cohen, Wired, 5 Nov. 2021 For those of us who can clearly remember beauty products before the start of the millennium, argan oil still has that new, buzzword feel. Marci Robin, Allure, 20 Oct. 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'millennium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of millennium

circa 1638, in the meaning defined at sense 1a

History and Etymology for millennium

New Latin, from Latin mille thousand + New Latin -ennium (as in biennium)

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Time Traveler for millennium

Time Traveler

The first known use of millennium was circa 1638

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Last Updated

19 Jan 2022

Cite this Entry

“Millennium.” Dictionary, Merriam-Webster, Accessed 28 Jan. 2022.

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More Definitions for millennium



English Language Learners Definition of millennium

: a period of 1,000 years
: a period of a thousand years counted from the beginning of the Christian era


mil·​len·​ni·​um | \ mə-ˈle-nē-əm How to pronounce millennium (audio) \
plural millennia\ -​nē-​ə \ or millenniums

Kids Definition of millennium

1 : a period of 1000 years
2 : a 1000th anniversary or its celebration

Other Words from millennium

millennial \ -​nē-​əl \ adjective


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