资料来源 : Webster's Revised Unabridged Dictionary (1913)

Lackadaisical \Lack`a*dai"si*cal\, a. [From {Lackadaisy},
   interj.]
   Affectedly pensive; languidly sentimental. --
   {Lack`a*dai"si*cal*ly}, adv.

资料来源 : WordNet®

lackadaisically
     adv : in an idle and lackadaisical manner; "he was hanging around
           the house lackadaisically"