rule

A regulation, law, guideline.

A regulating principle.

The act of ruling; administration of law; government; empire; authority; control.

A normal condition or state of affairs.

(obsolete) Conduct; behaviour.

(law) An order regulating the practice of the courts, or an order made between parties to an action or a suit.

(mathematics) A determinate method prescribed for performing any operation and producing a certain result.

A ruler; device for measuring, a straightedge, a measure.

A straight line (continuous mark, as made by a pen or the like), especially one lying across a paper as a guide for writing.

(printing, dated) A thin plate of brass or other metal, of the same height as the type, and used for printing lines, as between columns on the same page, or in tabular work.