The Collaborative International Dictionary of English v.0.48:

Imaginative \Im*ag"i*na*tive\, a. [F. imaginatif.]
   1. Proceeding from, and characterized by, the imagination,
      generally in the highest sense of the word.
      [1913 Webster]

            In all the higher departments of imaginative art,
            nature still constitutes an important element.
                                                  --Mure.
      [1913 Webster]

   2. Given to imagining; full of images, fancies, etc.; having
      a quick imagination; conceptive; creative.
      [1913 Webster]

            Milton had a highly imaginative, Cowley a very
            fanciful mind.                        --Coleridge.
      [1913 Webster]

   3. Unreasonably suspicious; jealous. [Obs.] --Chaucer. --
      Im*ag"i*na*tive*ly, adv. -- Im*ag"i*na*tive*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

imaginative
    adj 1: (used of persons or artifacts) marked by independence and
           creativity in thought or action; "an imaginative use of
           material"; "the invention of the knitting frame by
           another ingenious English clergyman"- Lewis Mumford; "an
           ingenious device"; "had an inventive turn of mind";
           "inventive ceramics" [syn: imaginative, inventive]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "imaginative":
   authentic, avant-garde, clever, conceptive, conceptual, contrived,
   creative, enterprising, esemplastic, expressive, fanciful,
   fantastic, fecund, fertile, fictional, fictitious, firsthand,
   fresh, germinal, graphic, ideational, ideative, ingenious,
   innovative, inspired, inspiring, inventive, meaningful, new,
   notional, novel, original, originative, poetical, pregnant,
   productive, prolific, resourceful, revolutionary, seminal, shaping,
   suggestive, teeming, underived, unique, visionary, visioned, vivid,
   whimsical