The Collaborative International Dictionary of English v.0.48:

Carelessly \Care"less*ly\, adv.
   In a careless manner.
   [1913 Webster]

WordNet (r) 3.0 (2006):

carelessly
    adv 1: without care or concern; "carelessly raised the
           children's hopes without thinking of their possible
           disappointment" [syn: carelessly, heedlessly]
    2: without caution or prudence; "one unfortunately sees historic
       features carelessly lost when estates fall into unsympathetic
       hands" [syn: incautiously, carelessly] [ant: carefully,
       cautiously]
    3: in a rakish manner; "she wore her hat rakishly at an angle"
       [syn: rakishly, raffishly, carelessly]

Moby Thesaurus II by Grady Ward, 1.0:

108 Moby Thesaurus words for "carelessly":
   a corps perdu, airily, any old way, any which way, anyhow,
   apathetically, at haphazard, at intervals, at random, bunglingly,
   by chance, by fits, by snatches, capriciously, casually, clumsily,
   cursorily, desperately, desultorily, disinterestedly,
   dispassionately, disregardfully, erratically, fitfully,
   forgetfully, furiously, haphazardly, happen what may, hastily,
   head over heels, headfirst, headforemost, headlong, heedlessly,
   heels over head, helter-skelter, hit and miss, hit or miss,
   holus-bolus, hotheadedly, hurriedly, hurry-scurry, impetuously,
   in snatches, in spots, inadvertently, inattentively,
   inconsiderately, indeliberately, indiscriminately, insouciantly,
   involuntarily, irregularly, lackadaisically, like crazy, like mad,
   listlessly, madly, messily, mindlessly, negligently, nonchalantly,
   offhand, offhandedly, once over lightly, overeagerly,
   overenthusiastically, overzealously, perfunctorily, precipitantly,
   precipitately, precipitously, promiscuously, ramble-scramble,
   randomly, recklessly, regardlessly, slam-bang, slap-bang, slapdash,
   sloppily, spasmodically, sporadically, tactlessly, thoughtlessly,
   unadvisedly, uncalculatedly, unconcernedly, undesignedly,
   unguardedly, unheedfully, unheedingly, unintentionally,
   uninterestedly, unmethodically, unmindfully, unpremeditatedly,
   unreasoningly, unsolicitously, unsystematically, unthinkingly,
   unthoughtfully, unvigilantly, unwarily, wantonly, wildly,
   without premeditation, without willing