The Collaborative International Dictionary of English v.0.48:

Distillation \Dis`til*la"tion\ (d[i^]s`t[i^]l*l[=a]"sh[u^]n), n.
   [F. distillation, L. destillatio.]
   1. The act of falling in drops, or the act of pouring out in
      drops.
      [1913 Webster]

   2. That which falls in drops. [R.] --Johnson
      [1913 Webster]

   3. (Chem.) The separation of the volatile parts of a
      substance from the more fixed; specifically, the operation
      of driving off gas or vapor from volatile liquids or
      solids, by heat in a retort or still, and the condensation
      of the products as far as possible by a cool receiver,
      alembic, or condenser; rectification; vaporization;
      condensation; as, the distillation of illuminating gas and
      coal, of alcohol from sour mash, or of boric acid in
      steam.
      [1913 Webster]

   Note: The evaporation of water, its condensation into clouds,
         and its precipitation as rain, dew, frost, snow, or
         hail, is an illustration of natural distillation.
         [1913 Webster]

   4. The substance extracted by distilling. --Shak.
      [1913 Webster]

   Destructive distillation (Chem.), the distillation,
      especially of complex solid substances, so that the
      ultimate constituents are separated or evolved in new
      compounds, -- usually requiring a high degree of heat; as,
      the destructive distillation of soft coal or of wood.

   Dry distillation, the distillation of substances by
      themselves, or without the addition of water or of other
      volatile solvent; as, the dry distillation of citric acid.


   Fractional distillation. (Chem.) See under Fractional.
      [1913 Webster]

WordNet (r) 3.0 (2006):

distillation
    n 1: the process of purifying a liquid by boiling it and
         condensing its vapors [syn: distillation, distillment]
    2: a purified liquid produced by condensation from a vapor
       during distilling; the product of distilling [syn:
       distillate, distillation]

Moby Thesaurus II by Grady Ward, 1.0:

163 Moby Thesaurus words for "distillation":
   aeration, aerification, artifact, atomization, blazing, blistering,
   bolting, brainchild, branding, burning, calcination, carbonization,
   cauterization, cautery, child, cineration, clarification, coinage,
   colature, combustion, composition, concentrate, concentration,
   concoction, concremation, condensation, core, cracking, creation,
   creature, cremation, crowning achievement, cupellation, decoction,
   deflagration, destructive distillation, disentanglement,
   disinvolvement, distillate, distilling, dribble, drip, dripping,
   drippings, drop, edulcoration, effect, elixir, elution,
   elutriation, end product, essence, essentialization,
   etherealization, etherification, evaporation, exhalation,
   expression, extract, extraction, fabric, filtering, filtration,
   flaming, fluidization, fractionation, fruit, fumigation,
   gasification, gist, handiwork, heart, incineration, infusion,
   invention, issue, kernel, leaching, leak, leakage, leaking,
   lixiviation, manufacture, marrow, masterpiece, masterwork,
   material, matter, meat, medium, mintage, narrowing, new mintage,
   nub, offspring, opera, opus, opuscule, origination, outcome,
   outgrowth, oxidation, oxidization, parching, percolation, pith,
   pressing, product, production, purification, pyrolysis,
   quintessence, refinement, refining, rendering, rendition, result,
   riddling, sap, scorching, scorification, screening, searing,
   seepage, seeping, self-immolation, separation, sieving, sifting,
   simplification, singeing, smelting, smoking, soaking, soul, spirit,
   spiritualization, spurtle, squeezing, steaming, steeping,
   straining, streamlining, stripping, stripping down, stuff,
   sublimation, substance, sum and substance, suttee, sweating,
   the stake, thermogenesis, trickle, tricklet, uncluttering,
   unscrambling, unsnarling, vaporization, vesication, volatilization,
   winnowing, work