The term 'WHODUNIT WHY' is a combination of two words, 'WHODUNIT' and 'WHY'. 'WHODUNIT' is a type of mystery novel or film in which the reader or viewer is challenged to solve a crime. The second word, 'WHY', refers to the MOTIVE behind the crime. In other words, the MOTIVE is the reason WHY the criminal committed the crime. Therefore, the term 'WHODUNIT WHY' can be used to refer to a mystery novel or film in which the reader or viewer must determine the MOTIVE behind the crime.