noun
Common
millennium
mih-LEH-neerm
Millennium (noun) means a period of one thousand years. Example: “Some ancient forests have survived for more than a millennium.”
noun
1
A period of one thousand years.
"Some ancient forests have survived for more than a millennium."
"Over a millennium, the small village slowly grew into a busy town."
"After millenniums of austerity and poverty, the age of limitless “superabundance” was at hand."
— Samuel Moyn, Can Democrats Learn to Dream Big Again? (2025)
"Historians study how civilisations rose and fell across a single millennium."
2
The point at which one thousand-year period ends and the next begins, especially the year 2000.
"Many people worried about computer problems as the millennium approached."
"He was born just before the millennium, so he barely remembers the old century."
"A huge fireworks display was put on in Sydney to celebrate the millennium."
"Cities across the world held huge parties to mark the new millennium."
How to use millennium
Learner’s notesIn plain EnglishA stretch of one thousand years, or the turning point between one such stretch and the next.
Common mistake
The plural is "millennia," not "milleniums."
Common pairings
the new millennium
turn of the millennium
for a millennium
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Word forms
- Plural
- millennia, millenniums
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Some ancient forests have survived for more than a _____.
Etymology
From Late Latin mīllennium, built from mīllennis ("of a thousand years") plus the noun-forming suffix -ium.
Synonyms
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Rhymes for millennium
See all rhymes for millennium →Frequently asked questions
What does “millennium” mean?
The word “millennium” means a period of one thousand years. In plain terms, a stretch of one thousand years, or the turning point between one such stretch and the next.
How do you pronounce “millennium”?
“Millennium” is pronounced mih-LEH-neerm (/mɪˈlɛnɪəm/ in IPA).
How do you use “millennium” in a sentence?
Here is “millennium” used in a sentence: “Historians study how civilisations rose and fell across a single millennium.”
What part of speech is “millennium”?
“Millennium” is a noun.
Where does the word “millennium” come from?
The word “millennium” comes from Late Latin. From Late Latin mīllennium, built from mīllennis ("of a thousand years") plus the noun-forming suffix -ium.
Is “millennium” a common word?
“Millennium” is a fairly common word in modern English.
How many meanings does “millennium” have?
“Millennium” has 2 distinct senses listed in this dictionary. The most common is: a period of one thousand years.
What is the difference between a millennium, a century, and a decade?
A decade is a period of ten years, a century is one hundred years, and a millennium is one thousand years. Each unit is ten times larger than the one before it, so a millennium contains ten centuries or one hundred decades.
Why is the year 2000 sometimes called "the millennium"?
The year 2000 marked the point where one thousand-year period ended and the next began, so it was widely referred to as "the millennium" in this narrower sense. This popular usage refers to the transition point itself rather than the full thousand-year span.
What is the plural of millennium?
The standard plural is "millennia," reflecting the word's Latin origin, though "millenniums" is also accepted in modern English. "Millennia" is more common in formal and academic writing.
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