for certain vs sure as shooting

for certain is not an adjective while sure as shooting is an adjective.

Word	Noun	Adjective	Verb	Adverb
for certain	No	No	No	Yes
sure as shooting	No	Yes	No	Yes

As adverbs, for certain and sure as shooting are synonyms defined as:

for certain and sure as shooting: definitely or positively (`sure' is sometimes used informally for `surely')

Other synonyms of for certain include certainly, for sure, sure, sure enough, surely.

for certain (adjective)	sure as shooting (adjective)
	absolutely certain

for certain (adverb)	sure as shooting (adverb)
definitely or positively (`sure' is sometimes used informally for `surely')	definitely or positively (`sure' is sometimes used informally for `surely')