# millennium

/məˈɫɛniəm/ (US) · /mɪlˈɛniəm/ (UK)

Source: https://englishreference.com/word/millennium
Updated: 2026-06-20

## Senses

### 1. one thousand years

noun · CEFR B2

a period of one thousand years.

For teachers: a span of time consisting of one thousand years.

- The ancient castle has stood for nearly a millennium.
- Archaeologists discovered evidence of a civilization that had thrived for over a millennium before suddenly vanishing from the historical record.

Usage: The plural form can be either 'millenniums' or the more formal 'millennia'.

Teaching tip: In academic writing, 'millennia' is the preferred plural form.

### 2. the year 2000

noun · CEFR B2

the specific time when one thousand-year period ends and another begins, especially the year 2000.

For teachers: the anniversary or transition point marking the end of one thousand-year cycle and the start of the next.

- Many people were worried about computer errors at the turn of the millennium.
- The celebrations for the new millennium were marked by spectacular firework displays in major cities across the globe.

Usage: Usually used with the definite article 'the'.

### 3. an era of peace

noun · CEFR C2 · Literary · Archaic

a long period of time in the future when everyone will be happy and peaceful.

For teachers: a hoped-for period of joy, serenity, and prosperity; often used in a religious or utopian context.

- The poet wrote about a coming millennium where war would no longer exist.
- The philosopher's vision of a secular millennium relied on the triumph of reason over tribalism.

Teaching tip: This sense is rare in modern conversation and is mostly found in older literature or religious texts.

## Examples

- The ancient ruins have stood for over a millennium.
- The world celebrated the start of a new millennium on January 1, 2000, with massive fireworks displays.
- Geologists measure the movement of tectonic plates over many millennia, as the slow shifts that shape our continents are imperceptible within a single human lifetime.

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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.