Merriam-Webster Collegiate Dictionary - mystery

 I. noun  (plural -teries)  Etymology: Middle English mysterie, from Latin mysterium, from Greek mysterion, from mystes initiate  Date: 14th century  1.  a. a religious truth that one can know only by revelation and cannot fully understand  b.  (1) any of the 15 events (as the Nativity, the Crucifixion, or the Assumption) serving as a subject for meditation during the saying of the rosary  (2) capitalized a Christian sacrament; specifically Eucharist  c.  (1) a secret religious rite believed (as in Eleusinian and Mithraic cults) to impart enduring bliss to the initiate  (2) a cult devoted to such rites  2.  a. something not understood or beyond understanding ; enigma  b. obsolete a private secret  c. the secret or specialized practices or ritual peculiar to an occupation or a body of people the mysteries of the tailor's craft  d. a piece of fiction dealing usually with the solution of a mysterious crime  3. profound, inexplicable, or secretive quality or character the ~ of her smile Synonyms:  ~, problem, enigma, riddle, puzzle mean something which baffles or perplexes. ~ applies to what cannot be fully understood by reason or less strictly to whatever resists or defies explanation the ~ of the stone monoliths. problem applies to a question or difficulty calling for a solution or causing concern problems created by high technology. enigma applies to utterance or behavior that is very difficult to interpret his suicide remains an enigma. riddle suggests an enigma or problem involving paradox or apparent contradiction the riddle of the reclusive pop star. puzzle applies to an enigma or problem that challenges ingenuity for its solution the thief's motives were a puzzle for the police.  II. noun  (plural -teries)  Etymology: Middle English ministry, office, craft, from Anglo-French mesterie, from Late Latin misterium, mysterium, alteration of ministerium service, occupation, from minister servant — more at minister  Date: 14th century  1. archaic trade, craft  2. archaic a body of persons engaged in a particular trade, business, or profession ; guild  3. ~ play