# millennia

/məˈɫɛniə/ (US) · /mɪlˈɛniə/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/millennia
Updated: 2026-05-07

## Definition

periods of time lasting one thousand years. You use this word when talking about very long stretches of history.

For teachers: plural form of 'millennium'; refers to multiple periods of one thousand years each.

## Examples

- These ancient trees have lived for several millennia.
- The landscape has been shaped by the slow movement of glaciers over many millennia.
- Archaeologists discovered layers of sediment that had accumulated over millennia, providing a detailed record of how the local climate shifted from lush forest to arid desert.

## Pitfalls

- Not "a millennia" but "a millennium" — Millennia is the plural form; use millennium when referring to a single thousand-year period.

## Usage notes

- The plural form of 'millennium'. Takes a plural verb and is often preceded by 'for' or 'over'.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.