Source : Webster's Revised Unabridged Dictionary (1913)

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
     adj : constituting or comprising a part or fraction of a possible
           whole or entirety; "a fractional share of the vote"; "a
           partial dose" [ant: {whole}]