The Collaborative International Dictionary of English v.0.48:

Unsuccessful \Un`suc*cess"ful\, a.
   Not successful; not producing the desired event; not
   fortunate; meeting with, or resulting in, failure; unlucky;
   unhappy. -- Un`suc*cess"ful*ly, adv. --
   Un`suc*cess"ful*ness, n.
   [1913 Webster]