'Variable quantity' definitions:

Definition of 'variable quantity'

noun

A quantity that can assume any of a set of values [syn: variable, variable quantity]

From: GCIDE

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. [1913 Webster]
2. Liable to vary; too susceptible of change; mutable; fickle; unsteady; inconstant; as, the affections of men are variable; passions are variable. [1913 Webster]
Lest that thy love prove likewise variable. --Shak. [1913 Webster]
His heart, I know, how variable and vain! --Milton. [1913 Webster]
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. [1913 Webster]
Syn: Changeable; mutable; fickle; wavering; unsteady; versatile; inconstant. [1913 Webster]