The Collaborative International Dictionary of English v.0.48:

Fractional \Frac"tion*al\, a.
   1. Of or pertaining to fractions or a fraction; constituting
      a fraction; as, fractional numbers.
      [1913 Webster]

   2. Relatively small; inconsiderable; insignificant; as, a
      fractional part of the population.
      [1913 Webster]

   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.
      [1913 Webster]

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):

fractional distillation
    n 1: fractionation of a liquid by distillation