mystery

mystery is a Noun

Definition:

[1] A profound secret; something wholly unknown, or something kept cautiously concealed, and therefore exciting curiosity or wonder; something which has not been or can not be explained; hence, specifically, that which is beyond human comprehension. We speak the wisdom of God in a mystery. 1 Cor. ii. 7. If God should please to reveal unto us this great mystery of the Trinity, or some other mysteries in our holy religion, we should not be able to understand them, unless he would bestow on us some new faculties of the mind. Swift.

[2] A kind of secret religious celebration, to which none were admitted except those who had been initiated by certain preparatory ceremonies; -- usually plural; as, the Eleusinian mysteries.

[3] The consecrated elements in the eucharist.

[4] Anything artfully made difficult; an enigma.