adjective

apt or liable to vary or change; changeable: variable moods.

variable weather;
variable moods.

Antonyms:

constant
capable of being varied or changed; alterable.

a variable time limit for completion of a book.
inconstant; fickle.

a variable lover.

Synonyms:

mercurial, unsteady, vacillating

Antonyms:

constant
having much variation or diversity.
Biology. deviating from the usual type, as a species or a specific character.
Astronomy. (of a star) changing in brightness.
Meteorology. (of wind) tending to change in direction.
Mathematics. having the nature or characteristics of a variable.

noun

variables
plural

something that may or does vary or change; a variable feature or factor.
Mathematics, Computers.
1. a quantity or function that may assume any given value or set of values.
2. a symbol that represents this.
Logic. (in the functional calculus) a symbol for an unspecified member of a class of things or statements.
Astronomy. variable star.
Meteorology.
1. a shifting wind, especially as distinguished from a trade wind.
2. variables, doldrums.

variable British

/ ˈvɛərɪəbəl /

adjective

liable to or capable of change

variable weather
(of behaviour, opinions, emotions, etc) lacking constancy; fickle
maths having a range of possible values
(of a species, characteristic, etc) liable to deviate from the established type
(of a wind) varying its direction and intensity
(of an electrical component or device) designed so that a characteristic property, such as resistance, can be varied

variable capacitor

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

something that is subject to variation
maths
1. an expression that can be assigned any of a set of values
2. a symbol, esp x, y, or z, representing an unspecified member of a class of objects, numbers, etc See also dependent variable independent variable
logic a symbol, esp x, y, z, representing any member of a class of entities
computing a named unit of storage that can be changed to any of a set of specified values during execution of a program
astronomy See variable star
a variable wind
(plural) a region where variable winds occur

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

variable Scientific

/ vâr′ē-ə-bəl /

A mathematical quantity capable of assuming any of a set of values, such as x in the expression 3 x + 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

Usage

What is a variable? In the context of scientific experiments, a variable is any factor that could change or be changed. So, for instance, if you’re measuring how effective a medication is, variables could include the amount of dosage, how frequently it’s taken, and the characteristics of each test subject, such as their age and weight. In general, variables are called variables because they vary. However, in scientific experiments, some variables are kept the same on purpose—such a variable is called a control variable (or sometimes simply just a control). There are three different types of variables: dependent variables, independent variables, and control variables. Independent variables are the factors that you change. Dependent variables are things that are affected by the changes that you make—the results of the tests (which depend on the independent variables). Control variables are the factors that you do not change. They are kept the same for every test or measurement in order to make sure that the results can be compared fairly. For example, let’s say you’re trying to figure out which brand of plant food will help a sunflower grow to the tallest height. The dependent variable is the final height of the sunflower. The independent variable (the factor that you change) is the brand of plant food. There are a number of other factors that could impact the growth of the plant, including things like the amount of sunlight and the amount of water. To allow for a proper comparison of the results, these need to be control variables—they need to be controlled, or kept the same. This way, you can have a greater degree of certainty that the final difference in heights (the dependent variable) is due to which food each sunflower received (the independent variable), not differences in sunlight or water. Properly setting the variables is crucial to scientifically sound experiments and studies.

Other Word Forms

Derived Forms

Inflected Forms

variables

plural

Etymology

Origin of variable

First recorded in 1350–1400; late Middle English, from Latin variābilis, equivalent to vari(us) “speckled, variegate, diverse” + -ābilis adjective suffix; see various, -able

Explanation

The adjective variable is used to describe something that is liable to change often, such as the weather, interest rates, or your teacher's mood. If you mention the noun variable to people who are math-phobic, you may give them nightmares because they don't like to think about numbers or values that can change in equations. The adjective form of variable has been around since the late 1300s, applying first to people, and then, in the late 1400s, to weather. The noun form first appeared in Lacroix's Differential and Integral Calculus in 1816, guaranteeing that math students would be solving for the variable x for generations to come.

Keep Reading on Vocabulary.com

Vocabulary lists containing variable

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

variable variables

The decisive variable in the war remains military manpower, said Gady, including whether Putin will launch a large-scale mobilization in the coming months to redouble his ground campaign.

From The Wall Street Journal ● Aug. 27, 2026

Just as important as hunting for a low interest rate is understanding whether the rate is fixed or variable.

From MarketWatch ● Aug. 24, 2026

Longer-range forecasts are always subject to change but there may be a little bit more into next week - but the amount of rain in any location may still be highly variable.

From BBC ● Aug. 11, 2026

A self-admitted overthinker, he considers every variable ad nauseum.

From Los Angeles Times ● Aug. 10, 2026

According to conventional nuclear physics, this was extraordinary, even bizarre: nuclei of different weights would be expected to emit disintegration products of widely variable energies, with the heavy elements producing the more energetic recoils.

From "Big Science" by Michael Hiltzik

"If we want to realize the potential of precision medicine, we have to understand these fundamental biological variables," says Professor Joseph Powell, co-senior author and Director of Garvan's Translational Genomics Program.

From Science Daily ● Aug. 20, 2026

We had the same director and it was like let’s remove as many variables as we can, since shooting a special is already kind of like a wild, weird experience.

From Los Angeles Times ● Aug. 18, 2026

That metric gauges how likely chances are to result in goals, taking into account a range of variables, and Arsenal finished with almost three times the xG total of City.

From BBC ● Aug. 16, 2026

Parameters are the variables that AI models use to learn and recognize patterns during training, and serve as a sort of memory.

From MarketWatch ● Jul. 20, 2026

It turns out that countries in regions with long histories of state societies or agriculture have higher per-capita GNP than countries with short histories, even after other variables have been controlled.

From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023