The Collaborative International Dictionary of English v.0.48:

Mystery \Mys"ter*y\, n.; pl. Mysteries. [OE. mistere, OF.
   mestier, F. m['e]tier, L. ministerium. See Ministry.]
   1. A trade; a handicraft; hence, any business with which one
      is usually occupied.
      [1913 Webster]

            Fie upon him, he will discredit our mystery. --Shak.
      [1913 Webster]

            And that which is the noblest mystery
            Brings to reproach and common infamy. --Spenser.
      [1913 Webster]

   2. A dramatic representation of a Scriptural subject, often
      some event in the life of Christ; a dramatic composition
      of this character; as, the Chester Mysteries, consisting
      of dramas acted by various craft associations in that city
      in the early part of the 14th century.
      [1913 Webster]

            "Mystery plays," so called because acted by
            craftsmen.                            --Skeat.
      [1913 Webster] Mystic

The Collaborative International Dictionary of English v.0.48:

Mystery \Mys"ter*y\ (m[i^]s"t[~e]r*[y^]), n.; pl. Mysteries
   (m[i^]s"t[~e]r*[i^]z). [L. mysterium, Gr. mysth`rion, fr.
   my`sths one initiated in mysteries; cf. myei^n to initiate
   into the mysteries, fr. my`ein to shut the eyes. Cf. Mute,
   a.]
   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.
      [1913 Webster]

            We speak the wisdom of God in a mystery. --1 Cor.
                                                  ii. 7.
      [1913 Webster]

            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.
      [1913 Webster]

   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.
      [1913 Webster]

   3. pl. The consecrated elements in the eucharist.
      [1913 Webster]

   4. Anything artfully made difficult; an enigma.
      [1913 Webster]

WordNet (r) 3.0 (2006):

mystery
    n 1: something that baffles understanding and cannot be
         explained; "how it got out is a mystery"; "it remains one
         of nature's secrets" [syn: mystery, enigma, secret,
         closed book]
    2: a story about a crime (usually murder) presented as a novel
       or play or movie [syn: mystery, mystery story,
       whodunit]

Moby Thesaurus II by Grady Ward, 1.0:

346 Moby Thesaurus words for "mystery":
   Chinese puzzle, Grand Guignol, Marchen, Passion play, Tom show,
   Western, Western story, Westerner, adventure story, allegory,
   ambiguity, ambiguousness, anagoge, anagogics, anthroposophy,
   antimasque, apologue, arcanum, art, audience success, awesomeness,
   baffle, bafflement, baffling problem, ballet, bedtime story,
   beguilingness, bewilderment, bomb, bother, brain twister,
   brain-teaser, broadcast drama, burlesque show, business, cabala,
   cabalism, career, career building, careerism, ceremonial, ceremony,
   charade, classified information, cliff hanger, closet drama,
   comedy drama, confidence, confidential communication, confoundment,
   confusion, conundrum, craft, critical success, crossword puzzle,
   crux, dark horse, daytime serial, detective novel, detective story,
   dialogue, dilemma, discomposure, disconcert, disconcertedness,
   disconcertion, disconcertment, disturbance, documentary drama,
   drama, dramalogue, dramatic play, dramatic series, duodrama,
   duologue, duty, eeriness, elfdom, embarrassment, enchantingness,
   enigma, enigmatic question, enigmaticalness, enticingness,
   epic theater, esoterica, esotericism, esoterics, esoterism,
   esotery, experimental theater, extraordinariness, extravaganza,
   fable, fabliau, faerie, failure, fairy tale, fantasy, fascination,
   fiction, fix, floorer, flop, folk story, folktale, form,
   form of worship, formality, formula, formulary, frontier,
   frontiers of knowledge, function, game, gasser, gest, ghost story,
   giveaway, glamorousness, guarded secret, handicraft, happening,
   hermetics, hit, hit show, hocus-pocus, holy rite, horse opera,
   improvisational drama, indefinability, indefiniteness,
   inexplicability, inextricability, inscrutability, insolvability,
   institution, jam, jigsaw puzzle, knot, knotty point, legend,
   legitimate drama, lifework, line, line of business, line of work,
   liturgy, love story, marvelousness, masque, matter of ignorance,
   melodrama, metier, mind-boggler, minstrel show, miracle,
   miracle play, miraculousness, mission, mode of worship, monodrama,
   monologue, morality, morality play, mumbo jumbo, music drama,
   musical revue, mysteriousness, mystery of mysteries, mystery play,
   mystery story, mysticism, mystification, myth, mythology, mythos,
   n, nebulousness, nonplus, number, numinousness, nursery tale,
   nut to crack, obscurity, observance, occultism, occupation, office,
   opera, order of worship, ordinance, otherworldliness, pageant,
   panel show, pantomime, parable, pastoral, pastoral drama,
   perplexed question, perplexity, personal matter, perturbation,
   phenomenalness, pickle, piece, play, playlet, plight, poser,
   pother, practice, predicament, prescribed form, preternaturalism,
   private matter, privileged communication, privity, problem,
   problem play, prodigiousness, profession, profound secret,
   psychodrama, pursuit, puzzle, puzzlement, puzzler, quandary,
   question, question mark, quiz show, racket, radio drama,
   remarkableness, restricted information, review, revue, riddle,
   rite, ritual, ritual observance, rituality, romance, sacrament,
   sacramental, science fiction, scrape, sealed book, secrecy, secret,
   seductiveness, sensational play, serial, service, shocker, show,
   sitcom, situation comedy, sixty-four dollar question, sketch, skit,
   soap, soap opera, sociodrama, solemnity, space fiction,
   space opera, specialization, specialty, spectacle, stage play,
   stage show, stew, sticker, straight drama, stumper, stupendousness,
   success, superhumanity, supernaturalism, supernaturality,
   supernaturalness, supernature, supernormalness, superphysicalness,
   supersensibleness, supranaturalism, supranature, suspense drama,
   suspense story, symbolics, symbolism, tableau, tableau vivant,
   talk show, teleplay, television drama, television play,
   terra incognita, the incalculable, the occult, the strange,
   the supernatural, the supersensible, the unfamiliar,
   the unknowable, the unknown, theater of cruelty, thriller,
   total theater, tough proposition, trade, transcendentalism,
   unaccountableness, unassuredness, undefinability, unearthliness,
   unexplainableness, unexplored ground, unexplored territory,
   unknown quantity, unworldliness, upset, vagueness, variety show,
   vaudeville, vaudeville show, vehicle, vexed question, vocation,
   walk, walk of life, whodunit, why, witchery, wonderfulness,
   wondrousness, word-of-mouth success, work, work of fiction, x,
   yoga, yogeeism, yogism, z



Easton's 1897 Bible Dictionary:

Mystery
   the calling of the Gentiles into the Christian Church, so
   designated (Eph. 1:9, 10; 3:8-11; Col. 1:25-27); a truth
   undiscoverable except by revelation, long hid, now made
   manifest. The resurrection of the dead (1 Cor. 15:51), and other
   doctrines which need to be explained but which cannot be fully
   understood by finite intelligence (Matt. 13:11; Rom. 11:25; 1
   Cor. 13:2); the union between Christ and his people symbolized
   by the marriage union (Eph. 5:31, 32; comp. 6:19); the seven
   stars and the seven candlesticks (Rev. 1:20); and the woman
   clothed in scarlet (17:7), are also in this sense mysteries. The
   anti-Christian power working in his day is called by the apostle
   (2 Thess. 2:7) the "mystery of iniquity."


Bouvier's Law Dictionary, Revised 6th Ed (1856):

MYSTERY or MISTERY. This word is said to be derived from the French mestier
now written metier, a trade. In law it signifies a trade, art, or
occupation. 2 Inst. 668.
     2. Masters frequently bind themselves in the indentures with their
apprentices to teach them their art, trade, and mystery. Vide 2 Hawk. c. 23,
s. 11.