Definition

1. Noun:
   • A measuring instrument: A ruler is a flat, straight-edged tool, typically made of wood, plastic, or metal, marked with units of length (like inches or centimeters) and used for drawing straight lines or measuring distances.
   • A sovereign or leader: A ruler is a person who governs or commands a country, state, or group of people, exercising authority and control.

Usage and Examples

• As a measuring instrument:
  • Use a ruler to draw a straight line.
  • The pencil is 15 centimeters long, as measured with a ruler.
• As a sovereign or leader:
  • The ancient ruler was known for his wisdom.
  • She was a just and fair ruler of her kingdom.

Advanced Usage

• "To be a ruler of": To be the person in control of a specific domain or field, not necessarily political.
  • He is a ruler of the local chess tournament, having won it five times.
• Metaphorical use for an instrument of measurement or standard:
  • The new policy will serve as a ruler for future decisions. (Here, "ruler" means a standard or guide for judgment.)

Variants and Related Words

• Rule (verb/noun): The action of governing or a principle guiding conduct. ()
• Rulership (noun): The position or period of rule. ()
• Measuring stick (noun): A synonym for the tool sense of "ruler."

Synonyms

• For the tool: Straightedge, measure, scale.
• For the person: Sovereign, monarch, leader, governor, commander.

Related Phrases and Idioms

• To rule with an iron fist/hand: To govern in a very strict and harsh manner.
  • The dictator was known to rule with an iron fist.
• As a rule: Usually; generally.
  • As a rule, she arrives at work early.
• To rule the roost: To be the person in charge of a place or group.
  • Everyone knows it's his grandmother who really rules the roost.

Noun

1. measuring stick consisting of a strip of wood or metal or plastic with a straight edge that is used for drawing straight lines and measuring lengths
2. a person who rules or commands
   • swayer of the universe