variable
noun
something that is likely to vary; something that is subject to variation
“the weather is one variable to be considered”
a quantity that can assume any of a set of values
Synonymsvariable quantitya star that varies noticeably in brightness
Synonymsvariable stara symbol (like x or y) that is used in mathematical or logical expressions to represent a variable quantity
adjective
liable to or capable of change
“rainfall in the tropics is notoriously variable”
“variable winds”
Oppositesinvariablemarked by diversity or difference
“the varying angles of roof slope”
“nature is infinitely variable”
Synonymsvarying(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”
Source: WordNet 3.1, Princeton University