Va·ri·a·ble a.
 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-rate mortgage Finance, a mortgage whose percentage interest rate varies depending on some agreed standard, such as the prime rate; -- used often in financing the purchase of a home.  Such a mortgage usually has a lower initial interest rate than a fixed-rate mortgage, and this permits buyers of a home to finance the purchase a house of higher price than would be possible with a fixed-rate loan.
 Variable stars Astron., fixed stars which vary in their brightness, usually in more or less uniform periods.
 Syn: -- Changeable; mutable; fickle; wavering; unsteady; versatile; inconstant.