# thin out

CEFR B2 · Phrasal verb

Source: https://englishreference.com/word/thin-out
Updated: 2026-07-28

## Definition

to make something less crowded or dense by removing some parts; it also describes when a group of people starts to leave so there are fewer left.

For teachers: to reduce the number or density of something in a specific area; can be used transitively (to remove items) or intransitively (to become less numerous).

## Examples

- The crowd begins to thin out after the main event.
- You should thin out the seedlings in the garden so the strongest plants have more room to grow.
- As the mist began to thin out, the jagged peaks of the mountain range finally became visible to the rescue team.

## Usage notes

- often used in gardening, hair care, or describing crowds and traffic.
- Teaching tip: use the image of a forest or a head of hair to explain density; contrast with 'thicken' as the natural opposite process.

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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.