Forgetful1. (a.) Apt to forget; easily losing remembrance; as, a forgetful man should use helps to strengthen his memory.
2. (a.) Heedless; careless; neglectful; inattentive.
3. (a.) Causing to forget; inducing oblivion; oblivious.
Thesaurus Entries
Lethean, absent, absent-minded, absentminded, abstracted, airy, amnesiac, amnestic, bemused, blocked, careless, casual, converted, cursory, degage, disregardant, disregardful, distracted, dreaming, dreamy, easygoing, flippant, forgetting, free and easy, heedless, in the clouds, inattentive, inclined to forget, inconsiderate, indifferent, insouciant, lax, lazy, mindless, neglectful, negligent, oblivious, offhand, out of it, perfunctory, preoccupied, reckless, regardless, remiss, remote, repressed, respectless, slack, suppressed, tactless, thoughtless, unaccommodating, uncomplaisant, uncooperative, undiplomatic, unheedful, unheeding, unhelpful, unmindful, unobliging, unprepared, unready, unsolicitous, untactful, unthinking, unthoughtful, unwitting