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]

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;
   indicative, significative, suggestive ; {meaty, substantive
   ; {purposeful] Also See: purposeful, significant,
   important.
   [WordNet 1.5]

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"

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