/ ˈmɪstri; NAmE / noun ( pl. -ies )
1.
[ C ] something that is difficult to understand or to explain :
It is one of the great unsolved mysteries of this century.
Their motives remain a mystery.
It's a complete mystery to me why they chose him.
2.
[ C ] (often used as an adjective) a person or thing that is strange and interesting because you do not know much about them or it :
He's a bit of a mystery.
There was a mystery guest on the programme.
The band was financed by a mystery backer.
( BrE )
a mystery tour (= when you do not know where you are going)
3.
[ U ] the quality of being difficult to understand or to explain, especially when this makes sb/sth seem interesting and exciting :
Mystery surrounds her disappearance.
His past is shrouded in mystery (= not much is known about it) .
The dark glasses give her an air of mystery .
4.
[ C ] a story, a film / movie or a play in which crimes and strange events are only explained at the end :
I enjoy murder mysteries.
5.
mysteries [ pl. ] secret religious ceremonies; secret knowledge :
( figurative )
the teacher who initiated me into the mysteries of mathematics
6.
[ C ] a religious belief that cannot be explained or proved in a scientific way :
the mystery of creation
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WORD ORIGIN
Middle English (in the sense mystic presence, hidden religious symbolism ): from Old French mistere or Latin mysterium , from Greek mustērion ; related to mystic .