variable vs changeable

variable is a noun but changeable is not a noun.

Word	Noun	Adjective	Verb	Adverb
variable	Yes	Yes	No	No
changeable	No	Yes	No	No

variable (noun)	changeable (noun)
a quantity that can assume any of a set of values
a symbol (like x or y) that is used in mathematical or logical expressions to represent a variable quantity
something that is likely to vary; something that is subject to variation
a star that varies noticeably in brightness

variable (adjective)	changeable (adjective)
liable to or capable of change	such that alteration is possible; having a marked tendency to change
(used of a device) designed so that a property (as e.g. light) can be varied	capable of or tending to change in form or quality or nature
marked by diversity or difference	varying in color when seen in different lights or from different angles
	subject to change