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[doo-al-i-tee, dyoo-] /duˈæl ɪ ti, dyu-/
a dual state or quality.
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.
Origin of duality
1350-1400; Middle English dualitie < Late Latin duālitās. See dual, -ity
Related forms
nonduality, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for duality
  • That's what makes him so edifying and infuriating to read: he sees duality everywhere.
  • The pursuit reveals the duality of the modern college.
  • Its duality instantly establishes the play's underlying dynamic between authority and anarchy.
  • There is a wave type duality between distance and time.
  • But that duality of spirit is the nature of homesteading.
  • Examples of this duality of purpose begin at the exterior.
  • In the past, both the sense of ambiguity and the theme of duality common to his work have been highly noticeable.
  • The duality as well as harmony presented in this painting is spectacular.
  • Such behavior leads to the quantum behavior of vacuum and particle-wave duality.
  • But what's really happening is the struggle of duality.
British Dictionary definitions for duality


noun (pl) -ties
the state or quality of being two or in two parts; dichotomy
(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
(geometry) the interchangeability of the roles of the point and the plane in statements and theorems in projective geometry
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for duality

late 14c., from Old French dualité (14c.), from Late Latin dualitas, from Latin dualis (see dual).

Online Etymology Dictionary, © 2010 Douglas Harper
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