The Collaborative International Dictionary of English v.0.48:

lackadaisical \lack`a*dai"si*cal\ (l[a^]k`[.a]*d[=a]"z[i^]*kal),
   a. [From Lackadaisy, interj.]
   1. Affectedly pensive; languidly sentimental; dreamy.
      [1913 Webster]

   2. Lacking spirit or liveliness; lethargic; listless;
      languid.
      [PJC]

   3. Indolent; lazy; idle, especially in a dreamy manner.
      [PJC] -- Lack`a*dai"si*cal*ly, adv.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lackadaisical
    adj 1: lacking spirit or liveliness; "a lackadaisical attempt";
           "a languid mood"; "a languid wave of the hand"; "a hot
           languorous afternoon" [syn: dreamy, lackadaisical,
           languid, languorous]
    2: idle or indolent especially in a dreamy way; "she was
       annoyingly lackadaisical and impractical";
       "a...lackadaisical, spiritless young man-about-town"-
       P.G.Wodehouse

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "lackadaisical":
   Micawberish, apathetic, ataractic, backward, benumbed, blase,
   bored, careless, casual, cold, cool, dallying, dead, debilitated,
   degage, delaying, devil-may-care, dilatory, dillydallying,
   disinterested, dispassionate, disregardful, dopey, dormant, droopy,
   drugged, dull, easy, easygoing, emasculated, enervated, exanimate,
   faineant, foot-dragging, free and easy, heavy, hebetudinous,
   heedless, idle, inactive, inanimate, inattentive, incurious,
   indifferent, indolent, inert, inexcitable, insouciant, jaded,
   laggard, lagging, languid, languishing, languorous, lax, lazy,
   leaden, lethargic, lifeless, limp, lingering, listless, loitering,
   lukewarm, lumpish, mindless, moribund, negligent, nonchalant, numb,
   offhand, passive, perfunctory, phlegmatic, pococurante, pooped,
   procrastinating, procrastinative, procrastinatory, reckless,
   regardless, remiss, romantic, sated, sentimental, shuffling, slack,
   sleepy, slothful, slow, sluggish, somnolent, spiritless, stagnant,
   stagnating, stultified, supine, tepid, torpid, turned-off,
   unanxious, uncaring, unconcerned, undiscriminating, unemotional,
   unenthusiastic, unexcitable, unexcited, unimpressed, uninspired,
   uninterested, unmindful, unmoved, unsolicitous, vegetable,
   vegetative, wan, weary, world-weary