ruler
Americannoun
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a person who rules or governs; sovereign.
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Also a strip of wood, metal, or other material having a straight edge and usually marked off in inches or centimeters, used for drawing lines, measuring, etc.
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a person or thing that rules paper, wood, etc.
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Astrology. the planet primarily associated with any sign of the zodiac or any house of the horoscope.
The ruler of Aries is Mars. The ruler of Taurus is Venus.
noun
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a person who rules or commands
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Also called: rule. a strip of wood, metal, or other material, having straight edges graduated usually in millimetres or inches, used for measuring and drawing straight lines
Other Word Forms
Etymology
Origin of ruler
Middle English word dating back to 1325–75; see origin at rule, -er 1
Explanation
The leader of a country is a ruler. If you're a queen, a sultan, or a czar, you're a ruler. Besides "person who rules or governs," you can define ruler as a measuring device that's marked with inches or centimeters. You can measure the diameter of a circle with a ruler, and you can also draw a perfectly straight line using its edge. Both meanings stem from the verb rule, "to exercise power" or "to control," which came to also mean "mark with lines" in the 1590s.
Vocabulary lists containing ruler
Measurement and Data, List 2
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"Culture Clash"
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Measurement and Data
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Biniam also produced three books that included collections of his work - Subtle is the Ruler, Conversation with Cobra Number One and Conversation with Cobra Number Two.
From BBC • Mar. 12, 2026
A corner stall in the stallion barn still bears Secretariat’s name and that of his sire, Bold Ruler, among those of other elites who have inhabited the space.
From Seattle Times • Jun. 10, 2023
He sired six champions around the world and such Grade 1 stakes winners as Bandini, Champ Pegasus, Haradasun and Roman Ruler.
From Washington Times • May 25, 2023
Andrei Skoch's blue and white "Madame Gu" was docked at Port Rashid on Friday, where Dubai's Ruler Sheikh Mohammed bin Rashid Al Maktoum keeps his own yacht, both visible to passersby.
From Reuters • Jun. 24, 2022
The High Ruler chooses their successor—that’s how the stability of Elfhame is ensured.
From "The Cruel Prince" by Holly Black
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
