Meaning : Being twofold. A classification into two opposed parts or subclasses.
Example :
The dichotomy between eastern and western culture.
Synonyms : dichotomy
Meaning : (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.
Synonyms : wave-particle duality
Meaning : (geometry) the interchangeability of the roles of points and planes in the theorems of projective geometry.