a cord with a lead bob attached to one end, used to determine perpendicularity, the depth of water, etc.Compare plumb(def 1).
Origin of plumb line
First recorded in 1530–40
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for plumb line
Historical Examples of plumb line
Will and the Professor were by the ice shaft, watching the plumb-line.
In the game way the stem and stern were measured with a plumb-line.
“Maybe you did not use the plumb-line, Master Leo,” observed Jack.
When I comes to rekillect how an' where he got that 'ere back, it looks to me like a plumb-line.
There is no plumb-line to measure the depths of thy shame, so deep is that abyss.
British Dictionary definitions for plumb line
a string with a metal weight at one end that, when suspended, points directly towards the earth's centre of gravity and so is used to determine verticality, the depth of water, etc
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
A line regarded as directed exactly toward the Earth's center of gravity.
The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.