Definition

Noun: A tool used in carpentry and masonry to check if a surface is perfectly vertical (plumb). It consists of a plumb line (a string with a weight) attached to a narrow, straight board.

Usage

The plumb rule is used to ensure walls, posts, or other structures are built straight up and down. * The carpenter used a plumb rule to check if the door frame was vertical. * Before laying the next course of bricks, verify the alignment with a plumb rule.

Advanced Usage

• Historical Context: The plumb rule is a traditional tool, largely replaced in modern construction by more advanced levels and laser tools, but it remains a fundamental and reliable instrument.
• Metaphorical Use: While rare, the principle of the plumb rule can be used metaphorically to mean a standard for judging correctness or uprightness.
  • His moral code was the plumb rule by which he measured all his decisions.

Variants and Related Words

• Plumb bob: The weighted, pointed metal tip at the end of a plumb line.
• Spirit level / Level: A more common modern tool containing a bubble in liquid to check for level (horizontal) and plumb (vertical) surfaces.
• Plumb line: The fundamental component (cord and weight) used for establishing a vertical reference.

Synonyms

• Plumb level
• Vertical gauge

Related Phrases

• To be out of plumb: Describes a surface or structure that is not perfectly vertical.
  • The old wall was several inches out of plumb.
• To plumb a wall: The action of using a plumb rule or plumb line to check a wall's verticality.
  • The mason took a moment to plumb the wall before continuing.

Noun

1. a plumb line attached to a narrow board