Synonyms for So Far (same or very similar meaning)
WordNet sense 1 (to the degree or extent that):
insofar, to that degree, to that extentWordNet sense 2 (used after a superlative):
yetWordNet sense 3 (used in negative statement to describe a situation that has existed up to this point or up to the present time):
heretofore, hitherto, up to now, as yet, thus far, til now, until nowFrom the ODE community, based on WordNetadd/edit