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]