This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

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

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.

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

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

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

"This duality is a manifestation of assumptions about the relationship between objects and ideas, much as Schäffer's color charts were, and they are limiting in similar ways. reference"

property    categorisation    classification    categorization    fungibility    interchangeableness    interchangeability    exchangeability   

the principle of duality   

wave-particle duality   

dichotomy   

abnormality    bisexuality    brutality    commonality    confidentiality    congeniality    criticality    dimensionality    extraterritoriality    finality   

oneness    dualism    plurality    totality    permanency    matter    body    estrangement    trinity