We use this word all the time to describe stuff we dont ā¦ Ā· mystery novels are often called āwhodunnitsā because they turn the reader into a detective trying to figure out the who, what, when, and how of a particular crime. See āmeaning & useā for definitions, usage, and quotation evidence. Mystery, problem, enigma, riddle, puzzle mean something which baffles or perplexes. There are six meanings listed in oeds entry for the noun mystery, three of which are labelled obsolete. Mystery noun anything that arouses curiosity or perplexes because it is unexplained, inexplicable, or secret: Definition of mystery noun in oxford advanced learners dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more. See examples of mystery used in a sentence. One that is not fully understood or that baffles or eludes the understanding; Something strange or not known that has not yet been explained or understood: The noun mystery comes from the greek mysterion, meaning secret rite or doctrine. a great synonym for secret is enigma. Mystery applies to what cannot be fully understood by reason or less strictly to whatever resists or ā¦ Ā· mystery (countable and uncountable, plural mysteries) something secret or unexplainable; Anything that is kept secret or remains unexplained or unknown.