heretofore vs as yet

heretofore and as yet both are adverbs.

Word	Noun	Adjective	Verb	Adverb
heretofore	No	No	No	Yes
as yet	No	No	No	Yes

As adverbs, heretofore and as yet are synonyms defined as:

heretofore and as yet: used in negative statement to describe a situation that has existed up to this point or up to the present time

Other synonyms of heretofore include hitherto, so far, thus far, til now, until now, up to now, yet.

heretofore (adverb)	as yet (adverb)
used in negative statement to describe a situation that has existed up to this point or up to the present time	used in negative statement to describe a situation that has existed up to this point or up to the present time