1387, of persons, from O.Fr. variable, from L. variabilis "changeable," from variare "to change" (see vary). Of weather, seasons, etc., attested from c.1480; of stars, from 1788. The noun meaning "quantity that can vary in value" first recorded 1816, from the adj.
liable to or capable of change; "rainfall in the tropics is notoriously variable"; "variable winds"; "variable expenses" [ant: invariable]
2.
marked by diversity or difference; "the varying angles of roof slope"; "nature is infinitely variable" [syn: varying]
3.
(used of a device) designed so that a property (as e.g. light) can be varied; "a variable capacitor"; "variable filters in front of the mercury xenon lights"
noun
1.
something that is likely to vary; something that is subject to variation; "the weather is one variable to be considered"
2.
a quantity that can assume any of a set of values
3.
a star that varies noticeably in brightness [syn: variable star]
4.
a symbol (like x or y) that is used in mathematical or logical expressions to represent a variable quantity
A mathematical quantity capable of assuming any of a set of values, such as x in the expression 3x + 2.
A factor or condition that is subject to change, especially one that is allowed to change in a scientific experiment to test a hypothesis. See more at control.
variableprogramming (Sometimes "var" /veir/ or /var/) A named memory location in which a program can store intermediate results and from which it can read it them. Each programming language has different rules about how variables can be named, typed, and used. Typically, a value is "assigned" to a variable in an assignment statement. The value is obtained by evaluating an expression and then stored in the variable. For example, the assignment x = y + 1 means "add one to y and store the result in x". This may look like a mathematical equation but the mathematical equality is only true in the program until the value of x or y changes. Furthermore, statements like x = x + 1 are common. This means "add one to x", which only makes sense as a state changing operation, not as a mathematical equality. The simplest form of variable corresponds to a single-word of memory or a CPUregister and an assignment to a load or storemachine code operation. A variable is usually defined to have a type, which never changes, and which defines the set of values the variable can hold. A type may specify a single ("atomic") value or a collection ("aggregate") of values of the same or different types. A common aggregate type is the array - a set of values, one of which can be selected by supplying a numerical index. Languages may be untyped, weakly typed, strongly typed, or some combination. Object-oriented programming languages extend this to object types or classes. A variable's scope is the region of the program source within which it represents a certain thing. Scoping rules are also highly language dependent but most serious languages support both local variables and global variables. Subroutine and functionformal arguments are special variables which are set automatically by the language runtime on entry to the subroutine. In a functional programming language, a variable's value never changes and change of state is handled as recursion over lists of values. (2004-11-16)
Con"stant\, n. 1. That which is not subject to change; that which is invariable. 2. (Math.) A quantity that does not change its value; -- used in countradistinction to variable. Absolute constant (Math.), one whose value is absolutely the same under all circumstances, as the number 10, or any numeral. Arbitrary constant, an undetermined constant in a differential equation having the same value during all changes in the values of the variables.
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. Syn: Changeable; mutable; fickle; wavering; unsteady; versatile; inconstant.
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