The Collaborative International Dictionary of English v.0.48:

Revelation \Rev`e*la"tion\, n. [F. r['e]v['e]lation, L.
   revelatio. See Reveal.]
   1. The act of revealing, disclosing, or discovering to others
      what was before unknown to them.
      [1913 Webster]

   2. That which is revealed.
      [1913 Webster]

   3. (Theol.)
      (a) The act of revealing divine truth.
      (b) That which is revealed by God to man; esp., the Bible.
          [1913 Webster]

                By revelation he made known unto me the mystery,
                as I wrote afore in few words.    --Eph. iii. 3.
          [1913 Webster]

   4. Specifically, the last book of the sacred canon,
      containing the prophecies of St. John; the Apocalypse or
      Book of Revelation or The Revelation of Saint John.
      [1913 Webster]

WordNet (r) 3.0 (2006):

revelation
    n 1: the speech act of making something evident [syn:
         disclosure, revelation, revealing]
    2: an enlightening or astonishing disclosure
    3: communication of knowledge to man by a divine or supernatural
       agency [syn: revelation, divine revelation]
    4: the last book of the New Testament; contains visionary
       descriptions of heaven and of conflicts between good and evil
       and of the end of the world; attributed to Saint John the
       Apostle [syn: Revelation, Revelation of Saint John the
       Divine, Apocalypse, Book of Revelation]

Moby Thesaurus II by Grady Ward, 1.0:

147 Moby Thesaurus words for "revelation":
   Christophany, Satanophany, admission, afflatus, angelophany,
   announcement, apocalypse, apparition, appearance, appearing,
   arising, astonishment, avatar, baring, blockbuster, blow, bomb,
   bombshell, bringing to light, bulletin, casual discovery, catch,
   catching, chance discovery, coming, coming into being,
   coming-forth, communique, confession, declaration, detection,
   determination, determining, direct communication, discernibleness,
   disclosing, disclosure, discovering, discovery, dissemination,
   distinguishment, divine inspiration, divine revelation,
   earthshaker, embodiment, emergence, epiphany, espial, evidence,
   evincement, excavation, exhumation, expose, exposition, exposure,
   expression, eye-opener, find, finding, finding out, forthcoming,
   incarnation, indication, information, inspiration, invention,
   issuance, joker, kicker, laying bare, leak, locating, location,
   lucky strike, manifestation, materialization, materializing,
   mystical experience, mysticism, news, observability, occurrence,
   opening, oracle, outcrop, outcropping, patefaction, perceptibility,
   peripeteia, pneumatophany, presentation, proclamation,
   pronouncement, proof, prophecy, publication, realization,
   recognition, rediscovery, removing the veil, revealing, revealment,
   rise, rising, seeableness, serendipity, shocker, showing,
   showing forth, showing up, showup, spotting, staggerer, startler,
   statement, strike, stripping, surprisal, surprise, surprise ending,
   surprise package, surprise party, switch, the seen, the visible,
   theophania, theophany, theopneustia, theopneusty, thunderbolt,
   thunderclap, treasure trove, trouvaille, trove, uncloaking,
   uncovering, unearthing, unfolding, unfoldment, unmasking,
   unveiling, unwrapping, visibility, visibleness, vision, visuality,
   what is revealed



Easton's 1897 Bible Dictionary:

Revelation
   an uncovering, a bringing to light of that which had been
   previously wholly hidden or only obscurely seen. God has been
   pleased in various ways and at different times (Heb. 1:1) to
   make a supernatural revelation of himself and his purposes and
   plans, which, under the guidance of his Spirit, has been
   committed to writing. (See WORD OF GOD.) The
   Scriptures are not merely the "record" of revelation; they are
   the revelation itself in a written form, in order to the
   accurate presevation and propagation of the truth.

     Revelation and inspiration differ. Revelation is the
   supernatural communication of truth to the mind; inspiration
   (q.v.) secures to the teacher or writer infallibility in
   communicating that truth to others. It renders its subject the
   spokesman or prophet of God in such a sense that everything he
   asserts to be true, whether fact or doctrine or moral principle,
   is true, infallibly true.


The Devil's Dictionary (1881-1906):

REVELATION, n.  A famous book in which St. John the Divine concealed
all that he knew.  The revealing is done by the commentators, who know
nothing.