variable
Adjective

Liable to or capable of change (synset 302514176)
also:
 inconsistent  displaying a lack of consistency
 inconstant  likely to change frequently often without apparent or cogent reason; variable
similar: changeable, uncertain, unsettled  subject to change
 covariant  changing so that interrelations with another variable quantity or set of quantities remain unchanged
 multivariate  pertaining to any procedure involving two or more variables
 protean  taking on different forms
 shifting  continuously varying
 variant  exhibiting variation and change
 versatile  changeable or inconstant
Noun

Something that is likely to vary
Something that is subject to variation (synset 109492089)hypernym: thing  a separate and selfcontained entity 
A quantity that can assume any of a set of values (synset 105866043)
hypernym: quantity  the concept that something has a magnitude and can be represented in mathematical expressions by a constant or a variablehyponym:
 argument  a variable in a logical or mathematical expression whose value determines the dependent variable; if f(x)=y, x is the independent variable
 experimental variable, independent variable  (statistics) a variable whose values are independent of changes in the values of other variables
 correlate, correlative  either of two or more related or complementary variables
 degree of freedom  (statistics) an unrestricted variable in a frequency distribution
 dependent variable  (statistics) a variable in a logical or mathematical expression whose value depends on the independent variable
 predictor variable  a variable that can be used to predict the value of another variable (as in statistical regression)
 infinitesimal  (mathematics) a variable that has zero as its limit
 chance variable, random variable, stochastic variable, variant, variate  a variable quantity that is random
 scalar  a variable quantity that cannot be resolved into components
 tensor  a generalization of the concept of a vector
 vector  a variable quantity that can be resolved into components
synonym: variable quantity 
A star that varies noticeably in brightness (synset 109492282)
hypernym: star  (astronomy) a celestial body of hot gases that radiates energy derived from thermonuclear reactions in the interiorinstance hyponym: north star, polar star, polaris, pole star, polestar  the brightest star in Ursa Minor; at the end of the handle of the Little Dipper; the northern axis of the earth points toward itsynonym: variable star

A symbol (like x or y) that is used in mathematical or logical expressions to represent a variable quantity (synset 107285985)
hypernym: symbol  an arbitrary sign (written or printed) that has acquired a conventional significancehyponym:
 placeholder  a symbol in a logical or mathematical expression that can be replaced by the name of any member of specified set
 unknown, unknown quantity  a variable whose values are solutions of an equation
Adjective

Marked by diversity or difference (synset 302517573)
similar: varied  characterized by varietysynonym: varying

(used of a device) designed so that a property (as e.g. light) can be varied (synset 301032411)
similar: adaptable  capable of adapting (of becoming or being made suitable) to a particular situation or use
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