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

Ultimately, the International Criminal Court charged Sudan's former dictatorial ruler Omar al-Bashir with genocide. —Patrick Reevell, ABC News, 28 Nov. 2025

From the beginning, the game held great power — Ottoman rulers even banned it, though Galatasaray players kept it alive. —Ben Croll, Variety, 28 Nov. 2025

Meanwhile your ruler Saturn brings the blueprint. —Dossé-Via Trenou, Refinery29, 28 Nov. 2025

Measure using a ruler — or even the short side of a credit card — to make sure that dense foods like stuffing and sweet potatoes reach a depth of no more than 2 inches (5 centimeters) to allow for quick and complete cooling in the refrigerator. —Jonel Aleccia, Fortune, 27 Nov. 2025

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