certainly vs sure as shooting

certainly is not an adjective while sure as shooting is an adjective.

Word	Noun	Adjective	Verb	Adverb
certainly	No	No	No	Yes
sure as shooting	No	Yes	No	Yes

As adverbs, certainly and sure as shooting are synonyms defined as:

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

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

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

certainly (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')