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

Iran has installed rulers even more conservative and hardline than their predecessors. —Mercury News & East Bay Times Editorial Boards, Mercury News, 7 May 2026

In the show Prince Adam is the son of Eternia’s rulers, King Randor and Queen Marlena. —Sanat Pai Raikarall, Encyclopedia Britannica, 4 May 2026

Singh died in 1839, and the Punjabi throne faced frequent changing of rulers for four years until Duleep Singh, a young boy, and his mother, Rani Jindan were left to take over. —Amethyst Martinez, USA Today, 30 Apr. 2026

The ensuing rulers, the Joseon monarchy, did their predecessors one better. —Lori Waxman, Chicago Tribune, 29 Apr. 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