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

Autocratic rulers need information to head off threats to their power; the CCP’s personnel file system, filled with information about the party’s cadres, is an irreplaceable channel of information for China’s rulers. — Andrew Mertha, Foreign Affairs, 17 Sep. 2026

House of the Dragon, meanwhile, specified that the prophecy was about a Targaryen ruler who would unite Westeros against a coming darkness from the far north. — Rafael Motamayor, Vulture, 15 Sep. 2026

After crash landing on the dark world directly onto the homing beacon, EO and his crazy crew are apprehended by a gang of warrior henchmen and hauled into the throne room to face the wicked alien ruler who is imprisoned in anger and hate. — Jeff Spry, Space.com, 15 Sep. 2026

The former is a liberal democracy, the latter a vicious dictatorship whose rulers kill their own people to stay in power. — Max Boot, Washington Post, 14 Sep. 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