duality
Americannoun
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a dual state or quality.
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Mathematics. a symmetry within a mathematical system such that a theorem remains valid if certain objects, relations, or operations are interchanged, as the interchange of points and lines in a plane in projective geometry.
noun
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the state or quality of being two or in two parts; dichotomy
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physics the principle that a wave-particle duality exists in microphysics in which wave theory and corpuscular theory are complementary. The propagation of electromagnetic radiation is analysed using wave theory but its interaction with matter is described in terms of photons. The condition of particles such as electrons, neutrons, and atoms is described in terms of de Broglie waves
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geometry the interchangeability of the roles of the point and the plane in statements and theorems in projective geometry
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of duality
1350–1400; Middle English dualitie < Late Latin duālitās. See dual, -ity
Explanation
As hinted at by the word "dual" within it, duality refers to having two parts, often with opposite meanings, like the duality of good and evil. If there are two sides to a coin, metaphorically speaking, there's a duality. Peace and war, love and hate, up and down, and black and white are dualities. Another term for a duality is a dichotomy. Duality has technical meanings in geometry and physics. In geometry, duality refers to how points and planes have interchangeable roles in projective geometry. In physics, duality is the property of matter and electromagnetic radiation to be understood best through wave theory or particle theory.
Vocabulary lists containing duality
It Takes Two: Di
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UCPS 6th Grade Roots List #5
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Dig
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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.
See Examples For:
In Mexico City, Mexican Americans displayed their fan duality by draping themselves in both nation’s flags and cheering for the U.S. when Mexico was not on the pitch.
From Los Angeles Times ● Jul. 11, 2026
Mabille's collection for haute couture week was all about getting more than you bargained for with its theme of duality.
From BBC ● Jul. 9, 2026
Marked by moody, lo-fi production, the group’s intense sophomore album explores the duality of despair and hope.
From The Wall Street Journal ● Jun. 30, 2026
The man’s duality was evident by the fact that he truly was the ugly, divisive character that spawned the nickname “Tricky Dick.”
From Salon ● May 14, 2026
The number-shape duality in Greek numbers made it easy; after all, zero didn’t have a shape and could thus not be a number.
From "Zero: The Biography of a Dangerous Idea" by Charles Seife
People are always going on about dualities: choice versus fate, protection versus destruction, stay versus go.
From Los Angeles Times ● Jun. 5, 2025
True to its title, its songs are full of dualities: angels and demons, grief and healing, dreams and realities, mirror images.
From New York Times ● Jun. 3, 2024
That speech America Ferrera gives in “Barbie” really highlights these impossible dualities that women have to embrace.
From Seattle Times ● Mar. 8, 2024
The city that’s been my home for 12 years has always been defined by its dualities and contrasts.
From New York Times ● Dec. 21, 2022
Then, from about 1994, people started discovering what are called dualities: different string theories and different ways of curling up the extra dimensions could lead to the same results in four dimensions.
From "A Brief History of Time: And Other Essays" by Stephen Hawking
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.
