ruler

noun

rul·​er ˈrü-lər 

1

: one that rules

specifically : sovereign

2

: a worker or a machine that rules paper

3

: a smooth-edged strip (as of wood or metal) that is usually marked off in units (such as inches) and is used as a straightedge or for measuring

rulership

ˈrü-lər-ˌship 

noun

Synonyms of ruler

• monarch
• emperor
• sovereign
• king

Examples of ruler in a Sentence

a summit attended by a number of rulers from around the world

This ruler shows inches and centimeters.

Recent Examples on the Web

The strikes, which Afghanistan's Taliban rulers said hit the eastern provinces of Khost, Kunar and Paktika, shattered more than a month of calm in the war. —CBS News, 10 June 2026

The humongous robot Voltron served as the defender of the universe, being the only weapon able to fight off the evil Galra Empire and its ruler, Zarkon (voiced by Neil Kaplan). —Sergio Pereira, Space.com, 10 June 2026

Also, with Mercury approaching its square to your taskmaster ruler, Saturn, emotional conversations require patience and discipline. —Valerie Mesa, PEOPLE, 9 June 2026

Past philosophers, such as Aristotle, emphasized the necessity of virtue in both the people and their rulers, and Montesquieu argued that virtue was the defining principle of republics. —Jordan Cash, The Conversation, 8 June 2026

Word History

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing ruler

• co-ruler

Rhymes for ruler

• cooler
• schooler
• schuller
• preschooler
• vestibular

Kids Definition

ruler

noun

rul·​er ˈrü-lər 

1

: sovereign entry 1 sense 1

2

: a straight strip of material (as wood or metal) marked off in units and used as a guide in drawing lines or for measuring