purposeful

from WordNet (r) 3.0 (2006)

purposeful
    adj 1: serving as or indicating the existence of a purpose or
           goal [ant: {purposeless}]
    2: having meaning through having an aim; "led a happy purposeful
       life"

from The Collaborative International Dictionary of English v.0.48

Purposeful \Pur"pose*ful\, a.
   Important; material. "Purposeful accounts." --Tylor. --
   {Pur"pose*ful*ly}, adv.
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

meaningful \meaningful\ adj.
   Having a meaning or purpose; having significance; as, a
   meaningful explanation; a meaningful discussion; a meaningful
   pause; to live a meaningful life. Opposite of {meaningless}.
   [Narrower terms: {comprehensible, understandable};

from Moby Thesaurus II by Grady Ward, 1.0

64 Moby Thesaurus words for "purposeful":
      advised, affirmed, aimed, aimed at, bound, bound and determined,
      calculated, certain, committed, confirmed, conscious, considered,
      contemplated, decided, decisive, dedicated, definite, deliberate,
      deliberated, designed, determined, devoted, dogged, earnest,
      envisaged, envisioned, firm, fixed, intended, intentional, knowing,
      meant, meditated, obstinate, of design, persevering, persistent,
      pertinacious, planned, positive, projected, proposed, purposed,
      purposive, relentless, resolute, resolved, serious, settled,
      sincere, single-minded, staunch, steadfast, strong-willed, studied,
      sure, teleological, tenacious, unfailing, unfaltering, voluntary,
      wholehearted, willful, witting