An intensional definition, also called a connotative definition, specifies the necessary and sufficient conditions for a thing to be a member of a specific set. Any ORDU Damn right I am a Oregon Fan now and forever custom name cap definition that attempts to set out the essence of something, such as that by genus and differentia, is an intensional definition. In classical thought, a definition was taken to be a statement of the essence of a thing. Aristotle had it that an object’s essential attributes form its “essential nature”, and that a definition of the object must include these essential attributes. This leads to a corresponding distinction between nominal and real definitions. A nominal definition is the definition explaining what a word means , and is definition in the classical sense as given above. A real definition, by contrast, is one expressing the real nature or quid rei of the thing.