The Collaborative International Dictionary of English v.0.48:

Fanciful \Fan"ci*ful\, a.
   1. Full of fancy; guided by fancy, rather than by reason and
      experience; whimsical; as, a fanciful man forms visionary
      projects.
      [1913 Webster]

   2. Conceived in the fancy; not consistent with facts or
      reason; abounding in ideal qualities or figures; as, a
      fanciful scheme; a fanciful theory.
      [1913 Webster]

   3. Curiously shaped or constructed; as, she wore a fanciful
      headdress.
      [1913 Webster]

            Gather up all fancifullest shells.    --Keats.

   Syn: Imaginative; ideal; visionary; capricious; chimerical;
        whimsical; fantastical; wild.

   Usage: Fanciful, Fantastical, Visionary. We speak of
          that as fanciful which is irregular in taste and
          judgment; we speak of it as fantastical when it
          becomes grotesque and extravagant as well as
          irregular; we speak of it as visionary when it is
          wholly unfounded in the nature of things. Fanciful
          notions are the product of a heated fancy, without any
          tems are made up of oddly assorted fancies, aften of
          the most whimsical kind; visionary expectations are
          those which can never be realized in fact. --
          Fan"ci*ful*ly, adv. -Fan"ci*ful*ness, n.
          [1913 Webster]

WordNet (r) 3.0 (2006):

fanciful
    adj 1: indulging in or influenced by fancy; "a fanciful mind";
           "all the notional vagaries of childhood" [syn:
           fanciful, notional]
    2: not based on fact; unreal; "the falsehood about some fanciful
       secret treaties"- F.D.Roosevelt; "a small child's imaginary
       friends"; "to create a notional world for oneself" [syn:
       fanciful, imaginary, notional]
    3: having a curiously intricate quality; "a fanciful pattern
       with intertwined vines and flowers"