Variable Va"ri*a*ble, n. 1. That which is variable; that which varies, or is subject to change. 2. (Math.) A quantity which may increase or decrease; a quantity which admits of an infinite number of values in the same expression; a variable quantity; as, in the equation x^2 - y^2 = R^2, x and y are variables. 3. (Naut.) (a) A shifting wind, or one that varies in force. (b) pl. Those parts of the sea where a steady wind is not expected, especially the parts between the trade-wind belts. Independent variable (Math.), that one of two or more variables, connected with each other in any way whatever, to which changes are supposed to be given at will. Thus, in the equation x^2 - y^2 = R^2, if arbitrary changes are supposed to be given to x, then x is the independent variable, and y is called a function of x. There may be two or more independent variables in an equation or problem. Cf. Dependent variable, under Dependent., 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.