# waterline

/wˈɔːtəlˌaɪn/ (UK) · CEFR B2 · Noun

Source: https://englishreference.com/word/waterline
Updated: 2026-10-18

## Definition

the line where the water meets the side of a ship or boat when it floats. You can often see it as a paint mark that shows how low the ship sits in the water.

For teachers: the line of contact between a floating vessel's hull and the water surface; also the painted mark indicating that level under specified loading conditions.

## Examples

- The waterline sits high when the boat is full.
- After loading the cargo, the crew checked the waterline to make sure the ship was not too low in the water.
- Algae stained the hull just above the waterline, recording months of slow passages through warm coastal waters.

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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.