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

• monarch
• sovereign
• emperor
• 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

Every ruler, every plan, every prophecy has been tested against the unruly currents of human will and the undertow of chance. —Jp Mangalindan, Time, 12 Sep. 2025

The song is the act’s second ruler and first sung by Jakob Nowell, son of late frontman Bradley Nowell. —Kevin Rutherford, Billboard, 12 Sep. 2025

More Hossein Beris/Getty Images What To Know Iranian lawmaker Mojtaba Zarei made the remarks on X, directly addressing the ruler of Qatar, Emir Sheikh Tamim bin Hamad Al Thani. —Amir Daftari, MSNBC Newsweek, 12 Sep. 2025

The title does not refer to the ruler who commissioned the first English Bible. —David Lyman, The Enquirer, 10 Sep. 2025

Word History

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing ruler

• co-ruler

Rhymes for ruler

• cooler
• jeweller
• 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