The Collaborative International Dictionary of English v.0.48:

Hitherto \Hith"er*to`\, adv.
   1. To this place; to a prescribed limit.
      [1913 Webster]

            Hitherto shalt thou come, but no further. --Job
                                                  xxxviii. 11.
      [1913 Webster]

   2. Up to this time; as yet; until now.
      [1913 Webster]

            The Lord hath blessed me hitherto.    --Josh. xvii.
                                                  14.
      [1913 Webster]

WordNet (r) 3.0 (2006):

hitherto
    adv 1: 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"; "the sun isn't up yet" [syn:
           so far, thus far, up to now, hitherto,
           heretofore, as yet, yet, til now, until now]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "hitherto":
   aforetime, already, as yet, before, before all, before now,
   beforetime, earlier, early, ere, ere then, erenow, erewhile, erst,
   formerly, here, heretofore, historically, in the past,
   in times past, once, only yesterday, or ever, prehistorically,
   previously, priorly, recently, so far, then, theretofore, thus far,
   up to now, whilom, yesterday, yet