uncertain vs sure thing

uncertain is not a noun while sure thing is a noun.

Word	Noun	Adjective	Verb	Adverb
uncertain	No	Yes	No	No
sure thing	Yes	No	No	No

uncertain (noun)	sure thing (noun)
	something that is certain

uncertain (adjective)	sure thing (adjective)
not established beyond doubt; still undecided or unknown
lacking or indicating lack of confidence or assurance
not certain to occur; not inevitable
not established or confirmed
ambiguous (especially in the negative)
not consistent or dependable
subject to change