foregone conclusion vs certain

foregone conclusion is a noun but certain is not a noun.

Word	Noun	Adjective	Verb	Adverb
foregone conclusion	Yes	No	No	No
certain	No	Yes	No	No

foregone conclusion (noun)	certain (noun)
something that is certain
an inevitable ending

foregone conclusion (adjective)	certain (adjective)
	established beyond doubt or question; definitely known
	having or feeling no doubt or uncertainty; confident and assured
	certain to occur; destined or inevitable
	established irrevocably
	exercising or taking care great enough to bring assurance
	definite but not specified or identified
	reliable in operation or effect