What does "fractional" mean?

Fractional: 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.