Source : Webster's Revised Unabridged Dictionary (1913)

Distillation \Dis`til*la"tion\, n. [F. distillation, L.
   destillatio.]
   1. The act of falling in drops, or the act of pouring out in
      drops.

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

   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.

   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.

   4. The substance extracted by distilling. --Shak.

   {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}.

Fractional \Frac"tion*al\, a.
   1. Of or pertaining to fractions or a fraction; constituting
      a fraction; as, fractional numbers.

   2. Relatively small; inconsiderable; insignificant; as, a
      fractional part of the population.

   {Fractional crystallization} (Chem.), a process of gradual
      and approximate purification and separation, by means of
      repeated solution and crystallization therefrom.

   {Fractional currency}, small coin, or paper notes, in
      circulation, of less value than the monetary unit.

   {Fractional distillation} (Chem.), a process of distillation
      so conducted that a mixture of liquids, differing
      considerably from each other in their boiling points, can
      be separated into its constituents.

Source : WordNet®

fractional distillation
     n : fractionation of a liquid by distillation