plumb line

noun

1. a cord with a lead bob attached to one end, used to determine perpendicularity, the depth of water, etc.

2. plumb rule.

plumb line

noun

1. 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

2. another name for plumb rule

plumb line

1. A line regarded as directed exactly toward the Earth's center of gravity.

Word History and Origins

Origin of plumb line¹

First recorded in 1530–40