# cluster

/ˈkɫəstɝ/ (US) · /klˈʌstɐ/ (UK)

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

## Senses

### 1. a small group

noun · CEFR B2

a group of similar things or people positioned closely together.

For teachers: a number of similar things or people growing or grouped together in a compact way.

- A small cluster of fans waited outside the hotel to see the singer.
- The researchers identified a cluster of rare plants growing near the riverbank, suggesting a unique microclimate in that specific area.

### 2. data or science

noun · CEFR C1 · Technical

a group of stars, data points, or cases of a disease that appear close together.

For teachers: a statistically significant grouping of data points, celestial bodies, or medical cases within a specific area or timeframe.

- The telescope revealed a bright cluster of stars in the center of the galaxy.
- Health officials investigated a cluster of respiratory infections reported within the same three-block radius over the last fortnight.

### 3. a chaotic mess

noun · CEFR C1 · Slang · Informal

a situation where everything goes wrong or is very messy.

For teachers: a chaotic or poorly managed situation; often used as a polite shortening of a more vulgar term.

- The morning commute was a total cluster because of the broken train.
- The product launch turned into a complete cluster when the servers crashed and the marketing team lost access to their accounts.

Usage: Often used in professional environments to avoid using the full vulgar expression 'clusterfuck'.

### 4. to gather together

verb · CEFR B2

to form a group or to move close together.

For teachers: to gather or grow into a cluster; to position objects or data into discrete groups.

- The children clustered around the teacher to hear the story.
- The cottages were clustered at the foot of the hill, protected from the harsh winds blowing off the Atlantic.

## Examples

- A small cluster of people stood near the entrance.
- The researchers noticed a cluster of unusual cases in the northern part of the city during the spring.
- The telescope revealed a dense cluster of stars at the galaxy's core, appearing as a single point of light to the naked eye but resolving into thousands of distinct bodies.

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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.