- In modern colloquial English, a mystery is a subgenre of detective fiction (see mystery fiction).
- Also in modern colloquial English, a mystery is something which is unknown.
- Originally mystery was a religious term. A mystery was a rite into which only the initiated were admitted. See in particular the article on mystery religion. In Eastern Christianity, and to a lesser extent in Catholicism, the seven sacraments are sometimes called "mysteries"; that nomenclature is perhaps inherited from ancient Greek religions.
- Another sense of the word mystery is defined by the Catholic Encyclopedia as "a supernatural truth ... that of its very nature lies above the finite intelligence".
- Mystery is the name of a chess engine. See Mystery (chess) .
