The quality or character of being twofold; dichotomy.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "duality" in a sentence
"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"
"Anyway, this duality is sort of like the electric and magnetic field duality."
"Taken collectively, science has its double dependence upon language and experience; but this duality is not significantly traceable into the statements of science taken one by one."