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

One of the biggest stores of historical data on that untapped mineral base is still in Belgium, DR Congo’s former colonial ruler, at the AfricaMuseum, which holds millions of geological records. — Ruben Nyanguila, semafor.com, 13 July 2026

The short poem with the ruler’s name as the title was published in 1818. — Sun Sentinel Editorial Board, Sun Sentinel, 13 July 2026

The two singles jointly rank as the third-longest-running rulers of all time, but perhaps not for long. — Hugh McIntyre, Forbes.com, 11 July 2026

During the visit — the first by a Canadian leader to Saudi Arabia in 26 years — Carney met with Saudi Crown Prince Mohammed bin Salman, the kingdom’s de facto ruler. — ABC News, 9 July 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