thus far vs until now

thus far and until now both are adverbs.

Word	Noun	Adjective	Verb	Adverb
thus far	No	No	No	Yes
until now	No	No	No	Yes

As adverbs, thus far and until now are synonyms defined as:

thus far and until now: used in negative statement to describe a situation that has existed up to this point or up to the present time

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

thus far (adverb)	until now (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