The Collaborative International Dictionary of English v.0.48:

Unmindful \Unmindful\
   See mindful.

WordNet (r) 3.0 (2006):

unmindful
    adj 1: not mindful or attentive; "while thus unmindful of his
           steps he stumbled"- G.B.Shaw [syn: unmindful,
           forgetful, mindless] [ant: aware, mindful]
    2: (followed by `to' or `of') lacking conscious awareness of;
       "oblivious of the mounting pressures for political reform";
       "oblivious to the risks she ran"; "not unmindful of the heavy
       responsibility" [syn: oblivious(p), unmindful(p)]

Moby Thesaurus II by Grady Ward, 1.0:

121 Moby Thesaurus words for "unmindful":
   Lethean, a stranger to, absentminded, airy, aloof, amnestic,
   apathetic, asleep, ataractic, blase, blind to, blocked, bored,
   careless, casual, caught napping, converted, cursory, dead to,
   deaf to, degage, detached, devil-may-care, disinterested,
   dispassionate, disregardant, disregardful, distant, distracted,
   distrait, easygoing, flippant, forgetful, forgetting,
   free and easy, heedless, impassive, impercipient, in ignorance of,
   inadvertent, inattentive, inclined to forget, incognizant,
   inconsiderate, incurious, indifferent, inexcitable, inobservant,
   insensible, insensible to, insouciant, lackadaisical, lazy,
   listless, mindless, napping, negligent, nonchalant, nonconceiving,
   not with it, oblivious, offhand, out of it, perfunctory,
   phlegmatic, pococurante, reckless, regardless, repressed,
   respectless, stolid, suppressed, tactless, thankless, thoughtless,
   turned-off, unaccommodating, unanxious, unappreciative, unaware,
   unaware of, uncomplaisant, unconcerned, unconscious,
   unconscious of, uncooperative, undiplomatic, undiscriminating,
   ungrateful, unhearing, unheedful, unheeding, unhelpful,
   uninquiring, uninsightful, uninterested, uninvolved, unknowing,
   unmarking, unmindful of, unnoticing, unnoting, unobliging,
   unobservant, unobserving, unperceiving, unprehensive, unprepared,
   unready, unrealizing, unremarking, unseeing, unsolicitous,
   unsuspecting, untactful, unthankful, unthinking, unthoughtful,
   unwitting, withdrawn, witless