The Collaborative International Dictionary of English v.0.48:

Careful \Care"ful\ (k[^a]r"f[.u]l), a. [AS. cearful.]
   1. Full of care; anxious; solicitous. [Archaic]
      [1913 Webster]

            Be careful [Rev. Ver. "anxious"] for nothing.
                                                  --Phil. iv. 6.
      [1913 Webster]

            The careful plowman doubting stands.  --Milton.
      [1913 Webster]

   2. Filling with care or solicitude; exposing to concern,
      anxiety, or trouble; painful.
      [1913 Webster]

            The careful cold beginneth for to creep. --Spenser.
      [1913 Webster]

            By Him that raised me to this careful height.
                                                  --Shak.
      [1913 Webster]

   3. Taking care; giving good heed; watchful; cautious;
      provident; not indifferent, heedless, or reckless; --
      often followed by of, for, or the infinitive; as, careful
      of money; careful to do right.
      [1913 Webster]

            Thou hast been careful for us with all this care.
                                                  --2. Kings iv,
                                                  13.
      [1913 Webster]

            What could a careful father more have done?
                                                  --Dryden.

   Syn: Anxious; solicitous; provident; thoughtful; cautious;
        circumspect; heedful; watchful; vigilant.
        [1913 Webster]

WordNet (r) 3.0 (2006):

careful
    adj 1: exercising caution or showing care or attention; "they
           were careful when crossing the busy street"; "be careful
           to keep her shoes clean"; "did very careful research";
           "careful art restorers"; "careful of the rights of
           others"; "careful about one's behavior" [ant: careless]
    2: cautiously attentive; "careful of her feelings"; "heedful of
       his father's advice" [syn: careful, heedful]
    3: unhurried and with care and dignity; "walking at the same
       measured pace"; "with all deliberate speed" [syn: careful,
       deliberate, measured]
    4: full of cares or anxiety; "Thou art careful and troubled
       about many things"-Luke 10.41
    5: mindful of the future in spending money; "careful with money"
       [syn: careful, thrifty]

Moby Thesaurus II by Grady Ward, 1.0:

120 Moby Thesaurus words for "careful":
   Scotch, accurate, advertent, agog, alert, all ears, all eyes,
   assiduous, attentive, aware, calculating, canny, cautious, chary,
   cheeseparing, circumspect, concentrated, conscientious,
   conscionable, conscious, conserving, considerate, critical,
   curious, deliberate, diligent, discreet, discriminating,
   discriminative, duteous, dutiful, earnest, economic, economizing,
   enlightened, exact, fastidious, finical, finicking, finicky,
   forehanded, foresighted, frugal, fussy, gingerly, guarded, heedful,
   hesitant, intense, intent, intentive, judgmatic, judicial,
   judicious, labor-saving, leaving out nothing, loving, meticulous,
   mindful, money-saving, nice, niggling, noncommittal, observant,
   observing, on guard, on the ball, on the job, open-eared,
   open-eyed, openmouthed, overconscientious,
   overlooking no possibility, overscrupulous, painstaking,
   parsimonious, particular, pawky, penny-wise, politic, precise,
   provident, prudent, prudential, punctilious, punctual, reflecting,
   reflective, regardful, religious, safe, saving, scrimping,
   scrupulous, skimping, slow to act, solicitous, spare, sparing,
   strict, studied, systematic, tender, tender-conscienced, tentative,
   thorough, thoughtful, thrifty, time-saving, unadventurous,
   uncommunicative, undaring, unenterprising, unprecipitate,
   unwasteful, vigilant, wary, watchful, well-advised, well-judged