from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The quality or character of being twofold; dichotomy.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A classification into two subclasses or opposed parts.
  • n. The interchangeability of points and planes.
  • n. The mathematical equivalence of two seemingly different theoretical descriptions of a physical system.

from the GNU version of the Collaborative International Dictionary of English

  • n. The quality or condition of being two or twofold; dual character or usage.

from The Century Dictionary and Cyclopedia

  • n. The state of being two, or of being divided into two; twofold division or character; twoness.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. (physics) the property of matter and electromagnetic radiation that is characterized by the fact that some properties can be explained best by wave theory and others by particle theory
  • n. being twofold; a classification into two opposed parts or subclasses
  • n. (geometry) the interchangeability of the roles of points and planes in the theorems of projective geometry


from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin duālitās.



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