The Collaborative International Dictionary of English v.0.48:

Bacchanal \Bac"cha*nal\, a. [L. Bacchanalis. See Bacchanalia.]
   1. Relating to Bacchus or his festival.
      [1913 Webster]

   2. Engaged in drunken revels; drunken and riotous or noisy.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bacchanal \Bac"cha*nal\ (b[a^]k"k[.a]*nal), n.
   1. A devotee of Bacchus; one who indulges in drunken revels;
      one who is noisy and riotous when intoxicated; a carouser.
      "Tipsy bacchanals." --Shak.
      [1913 Webster]

   2. pl. The festival of Bacchus; the bacchanalia.
      [1913 Webster]

   3. Drunken revelry; an orgy.
      [1913 Webster]

   4. A song or a dance in honor of Bacchus.
      [1913 Webster]

WordNet (r) 3.0 (2006):

bacchanal
    adj 1: used of riotously drunken merrymaking; "a night of
           bacchanalian revelry"; "carousing bands of drunken
           soldiers"; "orgiastic festivity" [syn: bacchanalian,
           bacchanal, bacchic, carousing, orgiastic]
    n 1: someone who engages in drinking bouts [syn: drunken
         reveler, drunken reveller, bacchanal, bacchant]
    2: a drunken reveller; a devotee of Bacchus [syn: bacchant,
       bacchanal]
    3: a wild gathering involving excessive drinking and promiscuity
       [syn: orgy, debauch, debauchery, saturnalia, riot,
       bacchanal, bacchanalia, drunken revelry]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "bacchanal":
   alcoholic, alcoholic addict, bacchanalia, bacchanalian, bat,
   bender, bibber, big drunk, binge, boozer, bout, bust, carousal,
   carouse, carouser, celebration, chronic alcoholic, chronic drunk,
   compotation, debauch, devotee of Bacchus, dipsomaniac, drinker,
   drinking bout, drunk, drunkard, drunken carousal, guzzle, guzzler,
   hard drinker, heavy drinker, imbiber, inebriate, jag, lovepot,
   oenophilist, orgy, party, pathological drinker, pot companion,
   potation, problem drinker, pub-crawl, reveler, saturnalia,
   serious drinker, shikker, soaker, social drinker, sot, spree,
   swigger, swiller, symposium, tear, thirsty soul, tippler, toot,
   toper, tosspot, wassail, wassailer, winebibber