mystery1

noun (plural mysteries)

• 1something that is difficult or impossible to understand or explain:the mysteries of outer space hoping that the inquest would solve the mystery
• the condition or quality of being secret, strange, or difficult to explain:much of her past is shrouded in mystery
• a person or thing whose identity or nature is puzzling or unknown:“He’s a bit of a mystery,” said Nina [as modifier]:a mystery guest

• 2a novel, play, or movie dealing with a puzzling crime, especially a murder.

• 3 (mysteries) the secret rites of Greek and Roman pagan religion, or of any ancient or tribal religion, to which only initiates are admitted.
• the practices, skills, or lore peculiar to a particular trade or activity and regarded as baffling to those without specialized knowledge:the mysteries of analytical psychology
• the Christian Eucharist.

• 4chiefly Christian Theology a religious belief based on divine revelation, especially one regarded as beyond human understanding:the mystery of Christ
• an incident in the life of Jesus or of a saint as a focus of devotion in the Roman Catholic Church, especially each of those commemorated during recitation of successive decades of the rosary.