Definition from Wiktionary, the free dictionary
- The quality of being mysterious.
- 1651, Jeremy Taylor, Twenty-Seven Sermons for the Summer Half-Year, Sermon II, Part II in ΕΝΙΑΥΤΟΣ: A Course of Sermons for All the Sundays of the Year, London: Tyler & Royston, 1668, p. 14, 
- This may seem strange; and indeed it is so: and it is one of the great mysteriousnesses of the Gospel.
- 1817, Jane Austen, Northanger Abbey, Chapter 5, 
- This sort of mysteriousness, which is always so becoming in a hero, threw a fresh grace in Catherine's imagination around his person and manners, and increased her anxiety to know more of him.
- 1920, Edith Wharton, The Age of Innocence, Book II, Chapter XXXIV, 
- His children had urged him to travel: Mary Chivers had felt sure it would do him good to go abroad and "see the galleries." The very mysteriousness of such a cure made her the more confident of its efficacy.
- 1970, Martin Buber, I and Thou, translated by Walter Kaufmann, New York: Charles Scribner's Sons, First Part, p. 56,
- And all this is not changed by adding "mysterious" experiences to "manifest" ones, self-confident in the wisdom that recognizes a secret compartment in things, reserved for the initiated, and holds the key, O mysteriousness without mystery, O piling up of information! It, it, it!
- 1651, Jeremy Taylor, Twenty-Seven Sermons for the Summer Half-Year, Sermon II, Part II in ΕΝΙΑΥΤΟΣ: A Course of Sermons for All the Sundays of the Year, London: Tyler & Royston, 1668, p. 14,