Source : Webster's Revised Unabridged Dictionary (1913)

Negligent \Neg"li*gent\, a. [F. n['e]gligent, L. negligens,p.
   pr. of negligere. See {Neglect}.]
   Apt to neglect; customarily neglectful; characterized by
   negligence; careless; heedless; culpably careless; showing
   lack of attention; as, disposed in negligent order. ``Be thou
   negligent of fame.'' --Swift.

         He that thinks he can afford to be negligent is not far
         from being poor.                         --Rambler.

   Syn: Careles; heedless; neglectful; regardless; thoughtless;
        indifferent; inattentive; remiss.

Source : WordNet®

negligent
     adj 1: characterized by neglect and undue lack of concern;
            "negligent parents"; "negligent of detail"; "negligent
            in his correspondence" [ant: {diligent}]
     2: marked by insufficient care or attention; "a negligent
        housekeeper"; "negligent about personal cleanliness"