Variable

adjective
1.
apt or liable to vary or change; changeable:
variable weather; variable moods.
2.
capable of being varied or changed; alterable:
a variable time limit for completion of a book.
3.
inconstant; fickle:
a variable lover.
4.
having much variation or diversity.
5.
Biology. deviating from the usual type, as a species or a specific character.
6.
Astronomy. (of a star) changing in brightness.
7.
Meteorology. (of wind) tending to change in direction.
8.
Mathematics. having the nature or characteristics of a variable.
noun
9.
something that may or does vary or change; a variable feature or factor.
10.
Mathematics, Computers.

a quantity or function that may assume any given value or set of values.
a symbol that represents this.

11.
Logic. (in the functional calculus) a symbol for an unspecified member of a class of things or statements.
Compare bound variable, free variable.
12.
Astronomy. variable star.
13.
Meteorology.

a shifting wind, especially as distinguished from a trade wind.
variables, doldrums (def 2a).

adjective
1.
liable to or capable of change: variable weather
2.
(of behaviour, opinions, emotions, etc) lacking constancy; fickle
3.
(maths) having a range of possible values
4.
(of a species, characteristic, etc) liable to deviate from the established type
5.
(of a wind) varying its direction and intensity
6.
(of an electrical component or device) designed so that a characteristic property, such as resistance, can be varied: variable capacitor
noun
7.
something that is subject to variation
8.
(maths)

an expression that can be assigned any of a set of values
a symbol, esp x, y, or z, representing an unspecified member of a class of objects, numbers, etc See also dependent variable, independent variable

9.
(logic) a symbol, esp x, y, z, representing any member of a class of entities
10.
(computing) a named unit of storage that can be changed to any of a set of specified values during execution of a program
11.
(astronomy) See variable star
12.
a variable wind
13.
(pl) a region where variable winds occur

variable var·i·a·ble (vâr’ē-ə-bəl, vār’-)
adj.

Likely to change or vary; subject to variation; changeable.

Tending to deviate, as from a normal or recognized type; aberrant.

Having no fixed quantitative value.

n.

Something that varies or that is prone to variation.

A quantity that is capable of assuming any of a set of values.

variable
(vâr’ē-ə-bəl)

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.

programming
(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 CPU register and an assignment to a load or store machine 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 function formal 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)