variable vs uncertain

variable is a noun but uncertain is not a noun.

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

variable (noun)	uncertain (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)	uncertain (adjective)
liable to or capable of change	not established beyond doubt; still undecided or unknown
(used of a device) designed so that a property (as e.g. light) can be varied	lacking or indicating lack of confidence or assurance
marked by diversity or difference	not certain to occur; not inevitable
	not established or confirmed
	ambiguous (especially in the negative)
	not consistent or dependable
	subject to change