being twofold; a classification into two opposed parts or subclasses
同义词：dichotomy
(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
同义词：wave-particle duality
(geometry) the interchangeability of the roles of points and planes in the theorems of projective geometry
duality详细解释
du.al.i.ty n.（名词）The quality or character of being twofold; dichotomy.两重性：具有两方面的性质或特点；一分为二
