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.
Anwar Gargash, a diplomatic adviser to the Emirates’ ruler, lashed out this week at the Gulf Cooperation Council, saying the position of the group representing the Arabian Peninsula’s monarchies “is the weakest in history.”
From The Wall Street Journal • Apr. 30, 2026
In U.A.E. villages near the Strait of Hormuz, such as Al Jeer, new posters show the Gulf monarchy’s ruler flanked by troops, jet fighters and helicopters.
From The Wall Street Journal • Apr. 3, 2026
Rebecca Ebbage, 32, says the day she started showing TSW symptoms was the day her skin became her "ruler".
From BBC • Mar. 28, 2026
"Only those nations ruled by kings or dictators display the image of their sitting ruler on the coins of the realm," he said.
From Barron's • Mar. 20, 2026
For after the ruler had returned from the mountain, all finally saw the madness in him.
From "When the Sea Turned to Silver" by Grace Lin
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.
