# cline

/ˈkɫaɪn/ (US) · /klˈaɪn/ (UK)

Source: https://englishreference.com/word/cline
Updated: 2026-08-27

## Senses

### 1. biological variation

noun · CEFR C2 · Academic · Technical

a slow change in a physical feature of a species across a large area.

For teachers: a gradation in a character or phenotype within a species or systematic group, typically along a geographical or environmental gradient.

- The birds show a cline in wing length, with longer wings found in the colder north.
- Ecologists observed a distinct morphological cline in the plant species as they sampled populations at increasing altitudes up the mountain range.

Usage: Often used with the preposition 'in' to describe the specific trait that is changing.

### 2. a gradual scale

noun · CEFR C2 · Academic

any range where one thing slowly turns into another without a clear break.

For teachers: a graduated continuum of any quality or state, where boundaries between categories are blurred.

- Linguists often view the difference between dialects as a cline rather than separate languages.
- The transition from formal to informal register is best understood as a stylistic cline rather than a set of rigid categories.

Usage: Frequently used in linguistics and sociology to describe non-binary transitions.

## Examples

- The cline in temperature is very noticeable as you move up the mountain.
- Biologists observed a cline in the size of the birds as they moved from the coastal regions to the interior forests.
- The study identified a sharp cline in genetic markers between the northern and southern populations, suggesting a recent barrier to gene flow that has persisted for several generations.

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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.