Source : Webster's Revised Unabridged Dictionary (1913)

Variable \Va"ri*a*ble\, a. [L. variabilis: cf. F. variable.]
   1. Having the capacity of varying or changing; capable of
      alternation in any manner; changeable; as, variable winds
      or seasons; a variable quantity.

   2. Liable to vary; too susceptible of change; mutable;
      fickle; unsteady; inconstant; as, the affections of men
      are variable; passions are variable.

            Lest that thy love prove likewise variable. --Shak.

            His heart, I know, how variable and vain! --Milton.

   {Variable exhaust} (Steam Eng.), a blast pipe with an
      adjustable opening.

   {Variable quantity} (Math.), a variable.

   {Variable stars} (Astron.), fixed stars which vary in their
      brightness, usually in more or less uniform periods.

Source : WordNet®

variable quantity
     n : a quantity that can assume any of a set of values [syn: {variable}]