The Collaborative International Dictionary of English v.0.48:

Virtually \Vir"tu*al*ly\, adv.
   In a virtual manner; in efficacy or effect only, and not
   actually; to all intents and purposes; practically.
   [1913 Webster]

WordNet (r) 3.0 (2006):

virtually
    adv 1: in essence or effect but not in fact; "the strike
           virtually paralyzed the city"; "I'm virtually broke"
    2: (of actions or states) slightly short of or not quite
       accomplished; all but; "the job is (just) about done"; "the
       baby was almost asleep when the alarm sounded"; "we're almost
       finished"; "the car all but ran her down"; "he nearly
       fainted"; "talked for nigh onto 2 hours"; "the recording is
       well-nigh perfect"; "virtually all the parties signed the
       contract"; "I was near exhausted by the run"; "most everyone
       agrees" [syn: about, almost, most, nearly, near,
       nigh, virtually, well-nigh]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "virtually":
   absolutely, actually, all in all, almost, almost entirely,
   approximately, as good as, basically, by and large, chiefly,
   effectively, effectually, essentially, fundamentally, in effect,
   in essence, in substance, in the main, latently, mainly, morally,
   more or less, mostly, nearly, on balance, on the whole,
   potentially, practically, substantially, underlyingly