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. Welcome, nephews, from successful wars. --Shak. Syn: Happy; prosperous; fortunate; auspicious; lucky. See Fortunate. -- Suc*cess"ful*ly, adv. -- Suc*cess"ful*ness, n.