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 company became a target in the legal fight to pay off creditors who lost oil assets, mining rights, and more when they were expropriated under Venezuela’s former socialist ruler, Hugo Chavez, almost 20 years ago. —Jordan Blum, Fortune, 9 Jan. 2026

Most of the vitriol has been aimed at the UAE, with Emiratis largely exercising restraint — and, unlike the Qatar episode, both are avoiding personal attacks on rulers (or their mothers). —Mohammed Sergie, semafor.com, 9 Jan. 2026

Composed of pictograms, the Azcatitlán’s 25 folios feature a succession of Aztec rulers, and dramatize the arrival of Hernán Cortés and Christianity. —Brittany Allen, Literary Hub, 8 Jan. 2026

Take the quiz here … CROWN FORGED – Landmark coin tied to legendary ruler preserved for nation after detectorist's lucky discovery. —FOXNews.com, 8 Jan. 2026

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