decideable vs computing

decideable is not a noun while computing is a noun.

Word	Noun	Adjective	Verb	Adverb
decideable	No	Yes	No	No
computing	Yes	No	No	No

decideable (noun)	computing (noun)
	the procedure of calculating; determining something by mathematical or logical methods
	the branch of engineering science that studies (with the aid of computers) computable processes and structures

decideable (adjective)	computing (adjective)
capable of being decided as following or not following from the axioms of a logical system