WordNet sense 1 (not showing due care or attention):

neglectful

WordNet sense 2 (characterized by neglect and undue lack of concern):

negligent

WordNet sense 3 (failing to keep in mind):

oblivious

WordNet sense 4 (showing lack of attention or boredom):

oscitant

WordNet sense 5 (dreamy in mood or nature):

dreamy

WordNet sense 6 (having the attention diverted especially because of anxiety):

distracted

WordNet sense 7 (lost in thought; showing preoccupation):

absent