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

Like the rulers of other European colonies, French colonial administrators sent in troops—known as the maréchaussée—to track down the maroon groups, but the French rarely negotiated. —Literary Hub, 5 Jan. 2026

An air of illegitimacy, particularly in the face of febrile nationalism, will undermine the new rulers. —Eliot A. Cohen, The Atlantic, 4 Jan. 2026

The capture of the brutal, illegitimate ruler of Venezuela, Nicolás Maduro, who oppressed Venezuela's people is welcome news for my friends and neighbors who fled his violent, lawless, and disastrous rule. —Cbs Miami Team, CBS News, 3 Jan. 2026

Lowell plunders an emerald out of a wrecked ship, starts a fistfight with a local ruler, nearly dies when a boa constrictor wraps itself around her neck, and is wounded by an alligator. —Michael Waters, New Yorker, 3 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