plumb bob: meaning, definition, pronunciation and examples
C1/C2Technical, Formal
Quick answer
What does “plumb bob” mean?
A heavy, pointed metal or brass weight, suspended from a string (plumb line), used in building and surveying to establish a true vertical line or to test for depth.
Audio
Pronunciation
Definition
Meaning and Definition
A heavy, pointed metal or brass weight, suspended from a string (plumb line), used in building and surveying to establish a true vertical line or to test for depth.
A tool or metaphor for establishing absolute verticality, precision, or a foundational reference point; sometimes used figuratively to denote a standard of truth or accuracy.
Dialectal Variation
British vs American Usage
Differences
Term is identical and standard in both dialects. The tool is universally known in relevant trades.
Connotations
Neutral and purely functional in both. No significant connotative difference.
Frequency
Equally low-frequency in general language but standard within technical domains in both regions.
Grammar
How to Use “plumb bob” in a Sentence
[Subject] + used/employed + a plumb bob + to + [Verb] (e.g., establish, check, align)The + plumb bob + [Verb] + [Adverbial] (e.g., hung, swung, pointed)Vocabulary
Collocations
Examples
Examples of “plumb bob” in a Sentence
verb
British English
- The mason will plumb the wall using a bob and line.
- He plumbed the corner for true vertical.
American English
- The carpenter plumbed the post with a bob.
- You need to plumb it before securing.
adverb
British English
- The wall was built plumb.
- Hold it plumb while I fix it.
American English
- The doorframe hangs plumb.
- Set the pole plumb in the hole.
adjective
British English
- The post was verified as plumb.
- Achieving a plumb line is critical.
American English
- Make sure the frame is plumb.
- A plumb measurement is essential.
Usage
Meaning in Context
Business
Not used.
Academic
Used in engineering, archaeology, architecture, and history texts discussing traditional building techniques.
Everyday
Virtually never used unless discussing DIY, construction, or historical tools.
Technical
Core term in construction, masonry, carpentry, and surveying for establishing a true vertical.
Watch out
Common Mistakes When Using “plumb bob”
- Misspelling as 'plum bob' (omitting the 'b').
- Confusing it with a 'spirit level'.
- Using it as a general term for any weight or tool.
FAQ
Frequently Asked Questions
No. A plumb bob establishes a true vertical line via a suspended weight. A spirit level (often just called a 'level') uses a bubble in liquid to check both horizontal and vertical surfaces.
Not directly. The tool is a noun. The related verb is 'to plumb,' meaning to measure depth or to test for verticality using a plumb bob or similar tool.
The word 'plumb' comes from the Latin 'plumbum' for lead, the heavy metal traditionally used to make the weight. 'Bob' refers to its free-swinging, bobbing motion.
No. It is a technical term specific to trades like construction, carpentry, and surveying. The average person may not know the term unless they have a background in these areas or serious DIY.
A heavy, pointed metal or brass weight, suspended from a string (plumb line), used in building and surveying to establish a true vertical line or to test for depth.
Plumb bob is usually technical, formal in register.
Plumb bob: in British English it is pronounced /ˌplʌm ˈbɒb/, and in American English it is pronounced /ˌplʌm ˈbɑːb/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “plumb the depths (related etymologically but not directly to the tool)”
Learning
Memory Aids
Mnemonic
Imagine a BOB (a common name) who is a PLUMBER. He uses a heavy, bobbing weight (a PLUMB BOB) to find the straight down 'plumb' line for his pipes.
Conceptual Metaphor
A PLUMB BOB IS A STANDARD OF TRUTH/PERFECT VERTICALITY (e.g., 'His moral compass was a plumb bob in a crooked world').
Practice
Quiz
In which field would you MOST likely encounter the term 'plumb bob' as a core tool?