The Collaborative International Dictionary of English v.0.48:

Fortunately \For"tu*nate*ly\, adv.
   In a fortunate manner; luckily; successfully; happily.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fortunately
    adv 1: by good fortune; "fortunately the weather was good" [syn:
           fortunately, fortuitously, luckily, as luck would
           have it] [ant: alas, regrettably, unfortunately,
           unluckily]