# flatten out

CEFR B2 · Phrasal verb

Source: https://englishreference.com/word/flatten-out
Updated: 2026-10-22

## Definition

to become flat or level, or to stop increasing and stay at the same level.

For teachers: To become level or even; to reach a plateau where a previous trend of increase or decrease ceases. The verb is typically intransitive in this sense, though it can be transitive when describing the physical act of making something flat.

## Examples

- The road flattens out after you pass the old farm.
- After two years of rapid growth, the company's profits began to flatten out this summer.
- Geological evidence suggests the terrain began to flatten out millions of years ago due to consistent glacial erosion across the plateau.

## Pitfalls

- Not "The runner was going flatten out." but "The runner was going flat out." — do not confuse the phrasal verb 'flatten out' with the idiom 'flat out', which means at maximum speed or effort.

## Usage notes

- usually describes a physical surface or a statistical trend like prices or growth.
- Teaching tip: useful for describing graphs and trends in business English; compare it with 'level off' which is a very close synonym.

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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.