# plumb

/ˈpɫəm/ (US) · /plˈʌm/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/plumb
Updated: 2026-05-19

## Definition

a heavy metal weight used to measure the depth of water. You drop it into the sea to see how deep the water is.

For teachers: a heavy lead weight used for measuring the depth of water. Often used in nautical contexts to determine the depth of a ship's keel or the depth of the sea.

## Examples

- The sailor dropped the plumb into the water.
- Before anchoring, the captain lowered a plumb to check the depth of the harbor floor.
- By measuring the time it took for the plumb to reach the seabed, the navigator could estimate the depth with a high degree of accuracy.

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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.