The Collaborative International Dictionary of English v.0.48:

Successful \Suc*cess"ful\, a.
   Resulting in success; assuring, or promotive of, success;
   accomplishing what was proposed; having the desired effect;
   hence, prosperous; fortunate; happy; as, a successful use of
   medicine; a successful experiment; a successful enterprise.
   [1913 Webster]

         Welcome, nephews, from successful wars.  --Shak.
   [1913 Webster]

   Syn: Happy; prosperous; fortunate; auspicious; lucky. See
        Fortunate.
        [1913 Webster] -- Suc*cess"ful*ly, adv. --
        Suc*cess"ful*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

successful
    adj 1: having succeeded or being marked by a favorable outcome;
           "a successful architect"; "a successful business venture"
           [ant: unsuccessful]

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "successful":
   affluent, ascendant, assured of success, bang, booming, celebrated,
   comfortable, comfortably situated, coming, conquering,
   crowned with success, defeating, dominant, easy, eminent,
   extraordinary, famed, famous, first, flourishing, flush,
   flushed with success, fortunate, fruitful, hit, in ascendancy,
   in clover, in good case, in luxury, in the ascendant, in the money,
   leading, loaded, lucky, lucrative, made, moneymaking, notable,
   noteworthy, on Easy Street, on the up-and-up, on top, on velvet,
   out in front, outstanding, overcoming, popular, prevailing,
   profitable, prominent, prospering, prosperous, remunerative,
   renowned, rich, smash, smashing, succeeding, surefire, thriving,
   top, triumphal, triumphant, vanquishing, victorious, wealthy,
   well-fixed, well-heeled, well-known, well-to-do, winning, wow