The Collaborative International Dictionary of English v.0.48:

Epiphany \E*piph"a*ny\, n. [F. ['e]piphanie, L. epiphania, Gr.
   'epifa`nia (sc. ?), for 'epifa`neia appearance, fr.
   'epifai`nein to show forth; 'epi` + fai`nein to show. See
   Fancy.]
   1. An appearance, or a becoming manifest.
      [1913 Webster]

            Whom but just before they beheld transfigured and in
            a glorious epiphany upon the mount.   --Jer. Taylor.
      [1913 Webster]

            An epic poet, if ever such a difficult birth should
            make its epiphany in Paris.           --De Quincey.
      [1913 Webster]

   2. (Eccl.) A church festival celebrated on the 6th of
      January, the twelfth day after Christmas, in commemoration
      of the visit of the Magi of the East to Bethlehem, to see
      and worship the child Jesus; or, as others maintain, to
      commemorate the appearance of the star to the Magi,
      symbolizing the manifestation of Christ to the Gentles;
      Twelfthtide.
      [1913 Webster]

WordNet (r) 3.0 (2006):

epiphany
    n 1: a divine manifestation
    2: twelve days after Christmas; celebrates the visit of the
       three wise men to the infant Jesus [syn: Epiphany,
       Epiphany of Our Lord, Twelfth day, Three Kings' Day,
       January 6]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "Epiphany":
   Advent, Allhallowmas, Allhallows, Allhallowtide, Annunciation,
   Annunciation Day, Ascension Day, Ash Wednesday, Candlemas,
   Candlemas Day, Carnival, Christmas, Corpus Christi, Easter,
   Easter Monday, Easter Saturday, Easter Sunday, Eastertide,
   Ember days, Good Friday, Halloween, Hallowmas, Holy Thursday,
   Holy Week, Lady Day, Lammas, Lammas Day, Lammastide, Lent,
   Lententide, Mardi Gras, Martinmas, Maundy Thursday, Michaelmas,
   Michaelmas Day, Michaelmastide, Palm Sunday, Pancake Day,
   Passion Week, Pentecost, Quadragesima, Quadragesima Sunday,
   Septuagesima, Shrove Tuesday, Trinity Sunday, Twelfth-day,
   Twelfth-tide, Whit-Tuesday, White Sunday, Whitmonday, Whitsun,
   Whitsunday, Whitsuntide, Whitweek



Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "epiphany":
   Christophany, Satanophany, afflatus, angelophany, apocalypse,
   apparition, appearance, appearing, arising, avatar, coming,
   coming into being, coming-forth, direct communication,
   discernibleness, disclosure, dissemination, divine inspiration,
   divine revelation, embodiment, emergence, evidence, evincement,
   exposure, expression, forthcoming, incarnation, indication,
   inspiration, issuance, manifestation, materialization,
   materializing, mystical experience, mysticism, observability,
   occurrence, opening, outcrop, outcropping, perceptibility,
   pneumatophany, presentation, proof, prophecy, publication,
   realization, revelation, rise, rising, seeableness, showing,
   showing forth, the seen, the visible, theophania, theophany,
   theopneustia, theopneusty, unfolding, unfoldment, visibility,
   visibleness, visuality, what is revealed