Used in negative statement to describe a situation that has existed up to this point or up to the present time:
— So far he hasn't called.

synonyms: as yet, heretofore, hitherto, thus far, til now, until now, up to now, yet.

Roget 106: while, whilst, during, pending; during the time, during the interval; in the course of, at that point, at that point in time; for the time being, day by day; in the time of, when; meantime, meanwhile; in the meantime, in the interim; ad interim, pendente lite [Lat.]; de die in diem [Lat.]; from day to day, from hour to hour &c.; hourly, always; for a time, for a season; till, until, up to, yet, as far as, by that time, so far, hereunto, heretofore, prior to this, up to this point.    the whole time, all the time; all along; throughout etc. (completely) 52; for good etc. (diuturnity) 110.    hereupon, thereupon, whereupon; then; anno Domini, A.   D.; ante Christum, A.   C.; before Christ, B.   C.; anno urbis conditae [Lat.], A.   U.C.; anno regni [Lat.], A.   R.; once upon a time, one fine morning, one fine day, one day, once.    ... show more

To the degree or extent that:
— So far as it is reasonably practical he should practice restraint.

synonyms: in so far, insofar, to that degree, to that extent.

Used after a superlative:
— This is the best so far.

synonym: yet.