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

With this week’s exit of Paramount+ streaming head Cindy Holland, Casey Bloys is the presumptive ruler of all streaming at Skydance. — Angelique Jackson, Variety, 2 Oct. 2026

Others have to do with the nature and trustworthiness of the regime in Riyadh, especially the country’s de facto ruler, Crown Prince Mohammed bin Salman. — Editorial Board, Washington Post, 1 Oct. 2026

The engineers who maintain an autocrat’s surveillance apparatus, for example, can shape what the ruler sees. — Seva Gunitsky, Foreign Affairs, 1 Oct. 2026

Correspondence to the point of conflation appeared in the sixteenth century, when rulers were nostalgic for the assurances of feudalism. — Sophie Landres, Artforum, 1 Oct. 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