DictionaryruleMeasuring tool
noun / verb

rule

A straightedge used to measure or guide lines.

She uses a steel rule to measure the board's width.

Etymology

Latin regula already named a straightedge. The physical tool preserves the literal guiding instrument behind the word’s broader sense of a standard.

More examples

  • The folding rule fits neatly in his toolbox.
  • Please rule a line beneath the heading.
  • He ruled the paper into columns before entering the totals.

Forms

rule · rules · ruled · ruling

ruler noun — A straightedge for measuring or drawing lines.

Similar words

ruler
The more common everyday name for a marked measuring straightedge.
straightedge
Guides straight lines but need not have measurement markings.