How to use mystery in a sentence. Synonym Discussion of Mystery. something strange or not known that has not yet been explained or understood: 2. mystery synonyms, mystery pronunciation, mystery translation, English dictionary definition of mystery. One that is not fully understood or that baffles or eludes the … Definition of mystery noun in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more. Definition, Usage, and a list of Mystery Examples. Mystery is a fiction genre where a murder or similar crime, remains mysterious until the end of the book. The mystery genre is a genre of fiction that follows a crime (like a murder or a disappearance) from the moment it is committed to the moment it is solved. Mystery novels are often called “whodunnits” … MYSTERY definition: anything that is kept secret or remains unexplained or unknown. See examples of mystery used in a sentence.