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 56-year-old cleric is the son of the late ruler Ali Khamenei, who was killed on February 28 during the opening phase of the war. —Sujita Sinha, Interesting Engineering, 9 Mar. 2026

Glass had chosen the pharaoh because he is thought to have been the first monotheistic ruler. —Classical Music Critic, Los Angeles Times, 6 Mar. 2026

An emergency summit is convened, where the genial George is joined by louder, angrier rulers from across the animal kingdom. —Justin Chang, New Yorker, 6 Mar. 2026

Kurds make up about a tenth of Iran’s population, and the ethnic group’s other national factions in Iraq and Syria have allied with the US in prior decades to fight those countries’ rulers. —Prashant Rao, semafor.com, 5 Mar. 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