副词

1. 迄今;到目前为止
You use hitherto to indicate that something was true up until the time you are talking about, although it may no longer be the case.

1. used in negative statement to describe a situation that has existed up to this point or up to the present time

e.g. So far he hasn't called
the sun isn't up yet

Synonym: so farthus farup to nowheretoforeas yetyettil nowuntil now