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 Pisces Moon in your finance zone squares your ruler Uranus in your playful 5th house, making spontaneous plans, tickets, hobbies, or treats harder to resist. — Tarot.com, Baltimore Sun, 24 Sep. 2026

The song follows two other rulers from the Better Late Than Never era, released in November 2025. — Pamela Bustios, Billboard, 23 Sep. 2026

Many key words from the slogan are coded deep in Xi Jinping Thought, the official political doctrine of China’s ruler. — Afra Wang, New Yorker, 23 Sep. 2026

The Aquarius Moon opposes your ruler Jupiter, making messages, ideas, research, travel plans, and future possibilities equally tempting. — Tarot.com, The Orlando Sentinel, 23 Sep. 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