plumb line

noun

A cord with a weight attached, used to produce a vertical line; a plummet.

Similar
perpendicular
OriginMiddle English plumblyne →
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Meanings

nounplumb line (plural plumb lines)

plural plumb lines · alternative plumbline

  1. A cord with a weight attached, used to produce a vertical line; a plummet.
  2. Any vertical reference line.

Synonyms & antonyms

nouna cord from which a metal weight is suspended pointing directly to the earth's center of gravity; used to determine the vertical from a given point

Similar
perpendicular
Broader
cord
Also see
perpendicularplumb

Synonym sets from Open English WordNet, CC BY 4.0.

Origin

  1. Middle Englishplumblyne
  2. Englishplumb line

From Middle English plumblyne, equivalent to plumb + line.

More words from Middle English

Full word history & related roots →
Cite this entry
APA

plumb line. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/plumb%20line

MLA

“plumb line.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/plumb%20line. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “plumb line,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/plumb%20line.

Source: plumb line on Wiktionary, CC BY-SA 4.0.