plumb line

noun

"plumb-line" is a 9-letter English headword indexed on PlainSpell.

The verdict

“plumb line” is uncommon English (outside the top frequency list), classed as a noun. The kind of spelling people second-guess.

Unranked
below top-frequency English
10
letters

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - A cord with a weight attached, used to produce a vertical line; a plummet.

Key facts for plumb line
PropertyValue
Headwordplumb line
LanguageEnglish
Part of speechNoun
Letters10
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “plumb line” sits in English frequency

plumb line falls outside the top-100,000 ranked English words, the long-tail zone of technical, archaic, or low-frequency vocabulary, exactly where readers second-guess spellings most.

Beyond rank #100,000. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

plumb line is uncommon English outside the top frequency list, classed as anoun. Rarity is why readers land here mid-draft. 2 senses are on record.

plumb line doesn't appear in our generated misspelling index, since its letter pattern doesn't lend itself to common typo substitutions. No close-neighbour confusable shows up for this headword in our dataset, suggesting its spelling stands apart enough that readers rarely confuse it with something else.

Etymologically, the entry records: From Middle English plumblyne, equivalent to plumb + line. The correct English form is plumb line, spelled P-L-U-M-B- -L-I-N-E.

Definition

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

Etymology

From Middle English plumblyne, equivalent to plumb + line.

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "plumb line"?
"plumb line" is spelled P-L-U-M-B- -L-I-N-E.
What does "plumb line" mean?
As a noun, "plumb line" means: A cord with a weight attached, used to produce a vertical line; a plummet.
What is the origin of the word "plumb line"?
From Middle English plumblyne, equivalent to plumb + line. See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Using “plumb line”

The practical upshot for anyone who landed here from a spell-check.

  • The one correct English spelling is P-L-U-M-B- -L-I-N-E - every other letter order is a misspelling in standard orthography.
  • Browse more English words and confusable pairs in the same reference. English words
Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list