What is "plumbline"

n. (alternative spelling of plumb line English)

A plumbline is a string with a lead ( Latin plumbum) weight or plumb-bob, used to provide a vertical reference line.

It may also refer to:

• The Plumbline, a joke newspaper produced by the McMaster Engineering Society
• In geodesy, a plumbline means the a line orthogonal to the geoid, the vertical direction