# boulder

/ˈboʊɫdɝ/ (US) · /bˈəʊldɐ/ (UK)

Source: https://englishreference.com/word/boulder
Updated: 2026-08-15

## Senses

### 1. a large rock

noun · CEFR B2

a very large, smooth rock that has been moved by water or ice.

For teachers: a large mass of stone detached from the surrounding land, typically worn smooth by erosion or glacial transport.

- The hikers sat on a giant boulder to eat their lunch by the river.
- Glacial activity thousands of years ago deposited massive granite boulders across the valley floor, creating a striking geological landscape.

### 2. climbing discipline

noun · CEFR C1 · Informal

a short climb on a small rock or indoor wall without using ropes.

For teachers: a session or specific problem in bouldering, a form of rock climbing performed on small rock formations without ropes or harnesses.

- He managed to finish a difficult boulder at the gym last night.
- The athlete spent the afternoon working on a technical boulder, focusing on the precise footwork required for the final overhang.

### 4. city in Colorado

noun · CEFR B2

a well-known city in the state of Colorado, USA, near the mountains.

For teachers: a home rule municipality and the county seat of Boulder County, Colorado, situated at the foothills of the Rocky Mountains.

- Many people visit Boulder to enjoy the outdoor lifestyle and hiking trails.
- Boulder is frequently cited as one of the most desirable places to live in the United States due to its proximity to the Flatirons.

## Examples

- The hikers sat on a large boulder to eat their lunch.
- Heavy rains caused several boulders to slide down the mountain and block the main highway.
- The landscape was dominated by massive granite boulders, smoothed over millennia by glacial movement and the relentless force of the surrounding river.

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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.